1) Getting started with Doppel

Main Doppel WindowThe main Doppel window

1.1) Adding folders and files for Doppel to scan

1.1a) Drag and drop the folders/files onto the middle of the main Doppel window.

1.1b) Drag and drop the folders/files onto the Doppel Icon Doppel icon (either in the Applications folder or the Dock).

1.1c) Click the Add button button and select the folders/files from the dialog.

1.1d) Select Scan and then the Add Items to List... menu item (or use the keyboard shortcut Cmd + O) and select the folders/files from the dialog.

1.1e) Select Duplicate Scan with Doppel from the Services menu while folders/files are selected in an application that supports services.

1.2) Removing folders and files from the main Doppel window

1.2a) Select the rows of the folders/files to remove and click the Remove button button.

1.2b) Select the rows of the folders/files to remove and press the Backspace key.

1.2c) Select Scan and then the New Scan menu item (or use the keyboard shortcut Cmd + N), this will remove all folders/files.

1.3) Starting the scan

1.3a) Click the Continue button button.

1.3b) Select Scan and then the Scan/Rescan menu item (or use the keyboard shortcut Cmd + R).

1.4) Scan progress

Scan ProgressScan progress

While the scan takes place, Doppel displays the progress along with the current stage.

Note: The scan may take a while, depending on the number and size of the files being scanned and the speed of the computer and drives being used.

1.5) Stopping the scan

Click the Cancel scan button button.

Note: The scan may take a few moments to stop while Doppel releases memory and closes any open files.

2) Processing the results

Results WindowThe results window

The results window is split into three panes, the left-hand pane shows the duplicate groups [see 2.1], the top-right pane shows the files or folders in the currently highlighted duplicate group [see 2.2] and the bottom-right shows either a pie chart breaking down the size of the duplicates by file type or, if one or more files are highlighted in the top-right pane, a preview of the file(s) content (if supported) [see 2.3].

2.1) Groups (left-hand pane)

The left-hand pane shows the duplicate groups, each group contains two or more files or folders which are considered to be duplicates of each other (or similar [see 2.2.6]).

GroupA group row

On the left side of each group an icon and name taken from one of the files/folders in the group (other files/folders may have different icons and names) and the size of all the files together is displayed.

On the right side, the number of files/folders in the group is shown in a bubble.
A grey Standard Group bubble is used if the group contains duplicates or a yellow Similar Group bubble if it contains similar [see 2.2.6] files.

Once one or more files in the group have been selected [see 2.2.1], the bubble shows the number selected and the total count as Group Selected (# selected | total #).

If all files/folders in a group are selected the bubble turns red Group All Selected to warn that all copies of this file/folder will be deleted [see 2.2.1.1]).

2.1.1) Sorting groups

Results can be sorted by Size (default, Descending), Name, Path, # of Duplicates and # of Selected.

The sort mode can be changed by selecting the Sort by ... menu at the top of the left-hand pane.

The sort can be changed to/from ascending/descending by reselected the same mode from the Sort by ... menu.

2.1.2) Filtering groups

Results can be filtered to show only duplicate groups of certain types via the Show: ... menu at the top of the left-hand pane.

The filter options available are:

  • All - show everything (default).
  • Folders - only show folders.
  • Movies - only show movie type files (mov, mp4, etc.).
  • Music - only show music/audio type files (mp3, wav, etc.).
  • Pictures - only show picture/image/photo type files (jpg, gif, etc.).
  • Documents - only show document type files (doc, pages, etc.).
  • Archives - only show archive (and disk image) type files (zip, rar, etc.).
  • Others - only show files not matching the above types.
  • Similar - only show files which are similar [see 2.2.6] but not a duplicate.
  • Unselected - only show groups which have more than one unselected file.

2.1.3) Auto Select Duplicates

2.1.3a) Click the Auto Select Duplicates button at the bottom of the groups list.

2.1.3b) Select Duplicates and then the Auto Select All Duplicates menu item (or use the keyboard shortcut Cmd + Shift + A).

This will apply the Auto Select [see 2.2.1] rules [see 3.3] to the groups in the groups list (if a filter is active, it will only apply to the groups matching the filter).

2.1.4) Deselect All

2.1.4a) Click the Deselect All button at the bottom of the groups list.

2.1.4b) Select Duplicates and then the Deselect All Duplicates menu item.

This will deselect all files/folders currently selected in the groups in the groups list (if a filter is active, it will only apply to the groups matching the filter).

2.2) Files (top-right pane)

The top-right pane shows the files or folders in the currently highlighted duplicate group.

FileA file row

A files row is made up of a selection checkbox File Unselected on the far left, followed by the file name and path. On the right side of the row is the modification date/time and the size.

Next to the size is the Reveal button button which will reveal the file/folder in the Finder.

Right-Click / Ctrl-Click on a file/folder to access Reveal in Finder and Open from the context menu.

Note: If a path is in bold, it means that although it hasn't matched with another folder, all of its contents are considered duplicates so using 'Select All Duplicates In...' [see 2.2.5] on the folder would result in the folder becoming empty and being removed [see 3.1.2]. This information can be useful to quickly organise large folders but is only a suggestion.

2.2.1) Selecting for deletion

Any file or folder can be selected for deletion, either manually via the checkbox or by using the automatic selection options.

Selected files/folders are displayed in the group list by the number (# selected) before the bar ("|") in the count bubble Group Selected and in the files list by a ticked checkbox File Selected.

Note: Copies to be kept must NOT be selected. Note: Groups containing similar [see 2.2.6] files are never automatically processed, the files must be manually reviewed and selected [see 2.2.1].

2.2.1.1) Selecting ALL files/folders for deletion

All the selection methods (other than manually ticking the checkbox) always leave at least one file/folder per group unselected.

Manually ticking the last unselected checkbox will trigger an alert (default, can be disabled), warning that all copies of this file/folder have be selected for deletion.

If the action is not cancelled (or the alert is disabled), the group bubble turns red Group All Selected to warn that all files/folders in this group have been selected.

Note: No additional warnings are given, please be careful, this could result in all copies of a file/folder being lost.

2.2.2) Select for Deletion: Auto, Newest, Oldest, None

The buttons at the top of the files list apply to all files/folders in the current group only.

2.2.2.1) The Auto button applies the Auto Select rules [see 3.3].

2.2.2.2) The Newest button selects the newest files/folders for deletion, leaving just the oldest file/folder unselected.

2.2.2.3) The Oldest button selects the oldest files/folders for deletion, leaving just the newest file/folder unselected.

2.2.2.4) The None button deselects all files/folders.

2.2.3) Manual selection

2.2.3a) Click on the File Unselected checkbox next to the file/folder to select.

2.2.3b) Press the Spacebar while file(s)/folder(s) are highlighted to toggle their selection state.

2.2.3c) Right-Click / Ctrl-Click on a file/folder and select Select for Deletion.

2.2.3d) Right-Click / Ctrl-Click on a file/folder and select Keep Only this Duplicate to select all other files/folders (and deselect the current) in the current group.

2.2.4) Manual deselection

2.2.4a) Click on the File Selected checkbox next to the file/folder to deselect.

2.2.4b) Press the Spacebar while file(s)/folder(s) are highlighted to toggle their selection state.

2.2.4c) Right-Click / Ctrl-Click on a file/folder and select Deselect.

2.2.4d) Right-Click / Ctrl-Click on a file/folder and select Keep Only this Duplicate to select all other files/folders (and deselect the current) in the current group.

2.2.5) Select All Duplicates In...

This will select any files/folders that are in (or in any subfolder of) the chosen folder, this is applied to all files/folder in all the groups in the groups list (if a filter is active, it will only apply to the groups matching the filter).

2.2.5a) Right-Click / Ctrl-Click on a file/folder and select Select All Duplicates in '...', this will use the parent folder of the current file/folder.

2.2.5b) Select Duplicates and then the Select All Duplicates In... menu item, this will open a dialog to choose the folder to use.

It is also possible to deselect any file/folder in a path: Right-Click / Ctrl-Click on a file/folder and select Deselect All in '...'.

2.2.6) Similar files

As well as finding duplicates, Doppel will also find similar files (default, can be disable).

A similar file is not the same as another file but has similarities in their content.

If maybe that one is a failed copy or download of another or one is slightly corrupted.

Similar files are show at the group level via a yellow Similar Group count bubble.

Note: Groups containing similar files are never automatically processed, the files must be manually reviewed and selected. Note: Extra care should be given when selecting similar files for deletion and should be reviewed throughly.

2.3) Preview (bottom-right pane)

The bottom-right shows either a pie chart breaking down the size of the duplicates by file type or, if one or more files are highlighted in the top-right pane, a preview of the file(s) content (if supported).

2.3.1) Pie chart

The pie chart simply breaks down the duplicates by file type (Folders, Movies, Music, Pictures, Documents, Archive and Other) and displays the total size of all files matching that type (files used in the Folders size are not added to the other file type sizes).

2.3.2) File previews

When a file/folder is highlighted, a preview of the file contents is displayed. It is possible to select up to six files and view the previews next to each other.

If multiple files are highlighted and their file type is a movie or music the previews will begin to play automatically (default, can be disabled [see 3.1.1]).

2.4) Remove Externally Deleted Items

Sometimes, it is easier and quicker to delete files/folder outsize of Doppel while reviewing the results.

When this happens, the results can get messy and it can be dangerous to use the automatic selection.

While it is possible to Rescan, this can and does take time.

Instead select Duplicates and then the Remove Externally Deleted Items menu item.

All files/folders (filtering does not apply) which no longer exist (and groups left with only one item) are removed from the results.

Note: Files added, moved or copied are not detected, a Rescan will be required.

2.5) Rescan

If changes (e.g., files added, moved) have been made to folders which were scanned, a rescan maybe required.

A rescan will close the current results and perform a scan on all files.

Select Scan and then the Scan/Rescan menu item (or use the keyboard shortcut Cmd + R).

2.6) Delete Selected Duplicates

To delete the files/folders that have been selected.

2.6.1a) Click the Delete Selected Duplicates button.

2.6.1b) Select Duplicates and then the Delete Selected Duplicates... menu item (or use the keyboard shortcut Cmd + Shift + Backspace).

Note: An alert (default, can be disabled) as well as a confirmation screen will be shown before deleting anything.

Before deleting anything, a confirmation screen will be shown, it displays the number of files/folders to be deleted as well as their total size.

If the screen is confirmed, all selected files/folders are moved to the Trash.

Click the Move to Trash button to confirm and move all selected files/folders to the Trash.

Click the Cancel button to dismiss the confirmation and return to the results.

Note: If confirmed, every selected file/folder in every group (filtering does NOT apply) will be moved to the Trash.

The deletion can take a few moments and the progress is show on the window. Once all files have been deleted, the index is then optimised.

The files/folders that were not selected will be regrouped, if new groups are found the new results are displayed.

If no groups are found, the results are closed and the main window shown.

Note: It is possible for new groups with 'new' files to appear, this is because a file could have be in a folder group (which are prioritised) but also have a match in a file group.

2.7) Back

Close the current results and return to the main window (and keep the folders/files added to the main window).

Click the Back to main window button.

2.8) New scan

Close the current results and return to the main window (and clear the folder/files added to the main window).

Select Scan and then the New Scan menu item (or use the keyboard shortcut Cmd + N).


3) Preferences

3.1) General Preferences

General PreferencesGeneral Preferences

3.1.1) Auto-Start Previews on Multiple Selection

When enabled, if multiple files are highlighted and their file type is a movie or music the previews will begin to play automatically.

3.1.2) Deleting - Remove Empty Folders

When enabled, folders made empty by deleting duplicates are automatically deleted.

3.1.3) Alerts

When enabled, the related alert dialog is not shown.

3.1.3.1) 'All Duplicates Selected' alert is shown if all the files/folders in a group are selected for deletion.

3.1.3.2) 'Similar Items Selected' alert is shown if a similar file is selected for deletion.

3.1.3.3) 'Deletion' alert is shown when choosing to Delete Selected Duplicates.

3.1.4) Updates (not shown on the Mac App Store version)

Choose to automatically check for updates, and if so the frequency to check.

3.2) Exclude Preferences

Exclude PreferencesExclude Preferences

3.2.1) Excluded Folders

Folders (and the files/folders they contain) added here will not be scanned, even if added directly to the main window.

Use the Add button and Remove button buttons to add/remove folders from the list (folders can also be dragged to the list).

3.2.2) Excluded Extensions

Any file found with a matching extension will not be scanned.

3.3) Auto Selection Preferences

Auto Selection PreferencesAuto Selection Preferences

3.3.1) Always Select

Add files/folders here to have them automatically selected when using the Auto Select buttons in the results window.

Use the Add button and Remove button buttons to add/remove files/folders from the list (files/folders can also be dragged to the list).

3.3.2) Never Select

Add files/folders here to ensure they are never automatically selected when using the automatic selection options in the results window (does not affect manual selection).

Use the Add button and Remove button buttons to add/remove files/folders from the list (files/folders can also be dragged to the list).

3.3.3) Also auto select

  • No - only use the files/folders in the Always Select list.
  • Newest - select from the Always Select list, and then select the newest files/folders, leaving just the oldest file/folder (or the files/folders in the Never Select list, if any).
  • Oldest - select from the Always Select list, and then select the oldest files/folders, leaving just the newest file/folder (or the files/folders in the Never Select list, if any).

Note: Use Also auto select with caution and remember to always check the results.

3.4) Advanced Preferences

Advanced PreferencesAdvanced Preferences

3.4.1) Index

This section allows the index to be optimised or purged.

Select a volume (or All Volumes for the entire index) from the dropdown menu.

3.4.1.1) Optimise

Optimise removes all records that point to files that no longer exist and so are no longer required.

Click the Optimise button to begin the optimisation, this may take a minute if the index is large, an alert will appear once it has finished.

Note: Optimise does not check if a volume is mounted, and so will remove records pointing to files on an unmounted volume.

3.4.1.2) Purge

Purge removes all records from the index.

Click the Purge button to begin the purge, an alert will appear once it has finished.

Note: Optimise and Purge only remove records in the Doppel index and no files/folders are affected.

3.4.2) Advanced

3.4.2.1) Disable Index

Enable this option to use Doppel without reading or writing to the index, this will slowdown repeated scans and have little effect on the speed of a single scan.

3.4.2.2) Disable Optimistic Index

To ensure Doppel is as fast as possible, the index is used Optimistically, and it is assumed that if a file has the same file size and modification date as the last time it was scan it has not changed, so the file is not re-hashed. Enable this option to force rehashing.

3.4.2.3) Disable Similar File Check

Doppel can detect files which while not duplicates are very similar, enable this option to stop checking for similar files and only report on duplicates.


A) Advanced

A.1) CLI

Doppel can be used from the command line (Terminal).

/Applications/Doppel.app/Contents/MacOS/Doppel [-lsadq] path ...

  • l - log information to the Terminal and Console.
  • s - start the scan immediately after launch.
  • a - apply auto select rules.
  • d - delete selected duplicates.
  • q - quit when finished.

Example: /Applications/Doppel.app/Contents/MacOS/Doppel -ls /path/to/folder /path/to/file /path/to/folder

Note: The CLI should be used with caution and only by those who understand the risks.