remove duplicates

Duplicate File Remover PRO

Technical Details, Features and Limitations

Duplicate File Remover Pro is an application to find duplicate files and clean up your Mac from them. The following document aims to bring the technical details of duplicates search and some restrictions of the app to your attention as well as provide you with valuable information so that you can strike the best results and performance when cleaning duplicates on your Mac.

System Requirements for Duplicate File Remover Pro

  • macOS 10.10 or later
  • 64-bit processor
  • 30 MB free disk space
  • 4 GB RAM

Files and Volumes Support

  • Duplicate File Remover Pro scans any type of volume:
  • Internal Mac hard drive
  • External Drives
  • Network Disks
  • Separate folders on internal and external drives
  • Synchronized folders from Cloud storages on a Mac

Duplicate File Remover Pro finds duplicates of any file type:

  • Photos
  • Music
  • Video
  • Documents
  • Archives
  • Folders
  • And others

Duplicate File Remover Pro DOES NOT find the following types of duplicate files:

  • Emails
  • Contacts
  • Calendar notes
  • Similar pictures (pictures that look alike, but they are not identical. Learn more about this in the Duplicates Search Algorithm section).

Family Sharing

Duplicate File Remover Pro does support Family Sharing. Learn how to use Family Sharing on the Apple Support page.

Finding Duplicates in the Photos App

Please note, that Duplicate File Remover Pro is an app to find duplicate files on regular disks and folders. The app is not intended to search for identical images inside the Mac Photos application because all pictures there are kept inside special packages. Nevertheless, you can scan the photos if you unfold the package and select images from its subfolders.

Duplicate Searching Algorithm

Duplicate File Remover Pro compares files accurately using three main characteristics – their sizes, extensions, and binary data. In the first step it finds the files of the same file extension type, then it compares their sizes. If two or more files with the same extensions have the same size, they are then compared using their binary data. The application never takes the filename into account because computer users can always rename identical files or give different files the same name, so the results would not be accurate. Duplicate files are files, which have an identical type, size, and binary data.

Duplicates Scanning Speed

The scanning speed of the app depends on the following factors:

  • The number of duplicate files.
  • The total size of scanned folders/volumes.
  • The scan speed of the disk.
  • The app’s scan preferences.

If you scan an external disk with a huge number of files and the disk is connected to your Mac via USB2.0, the scanning time may take up even several hours. You can decrease the scan time using Preferences of Duplicate File Remover Pro. Learn More >>

Features of Duplicate File Remover Pro

  • Find all duplicate files and folders.
  • Remove duplicate files and folders.
  • Scan any drive type supported by macOS.
  • Use the QuickLook option to preview duplicates.
  • View the duplicate files directory and quickly open them in the Finder.
  • Auto-Select duplicates.
  • Add files and folders to the Skip List.
  • Sort duplicates by different categories (type, name, count, path, size).
  • Regulate the size of files that should be scanned.
  • Use duplicates cleanup hints.
  • Preview removal history.
  • Find Similars folders.
  • Merge Similar folders
  • Find hidden duplicate files.
  • Specify folders to select duplicates in.
  • Restore removed duplicates.

Duplicates Removing

After duplicates selecting and clicking to remove them, Duplicate File Remover Pro displays a confirmation screen with a list of all selected duplicates. Please, check them carefully and make sure you don’t need them anymore. And only then confirm the removal of them.

Merge Folders Option

With Duplicate File Remover Pro you can review Similar folders and merge them. Similar folders are the folders which contain both duplicate and identical files.

How Does Auto Select Work?

  1. Duplicate File Remover Pro checks if scanned duplicates are still alive (as you could delete them after the scan, e.g. from Finder);
  2. Duplicate files then are checked with Never Select and Always Select lists. If they are presented there the app does skip or select files respectively.
  3. The program selects files that have similar names like: “Copy of filename”, “Filename – 2” or “Filename (2)”.
  4. If the files have identical names the app goes up and checks folders by the same scenario.

Note, the app always keeps one original file. You can navigate to duplicates group and click arrow right to Auto Select button highlighted red. And choose one of the options: Auto select oldest and Auto select newest.

Removing All Duplicate Files, Including the Original File

By default the option to select and remove all duplicate copies is disabled. When you select files, the program keeps one file as original. But you can change this option in the Preferences → Remove tab. Also, if you try to select all duplicates, you will see a notification asking you to allow removing all duplicate copies.

Resolving Issues When Some Duplicates Cannot be Removed

Sometimes you may get a message that the app cannot remove duplicate files. There are several reasons for this:

  • You are trying to remove files from an external drive which is mounted as read-only. For example, you mount NTFS external disk and don’t have a special driver to make the disk writable on Mac. You should, therefore, install the necessary system extension (NTFS driver) to allow removal of the duplicates. Learn more >>
  • You are trying to remove files from an external volume that does not have the Trash folder as yet. By default, Duplicate File Remover Pro moves files to the Trash. If no Trash folder has been created, the app does not have enough permission to remove a file. You should switch to Finder window and from there remove any unneeded file on that external drive/volume. The Trash for external volume will then be created, after which Duplicate File Remover Pro can remove identical files. Another solution for such an issue is to remove files or folders permanently. In this case, Duplicate File Remover Pro will require your confirmation to delete files permanently. If it suits you, confirm the removal. Learn more >>
  • Your files might be locked. Check file permissions – select a file/ folder in the Finder, use CMD+I shortcut to verify the permissions. Learn more >>
  • Your files might be used by another application.

Restoring Removed Duplicates

Sometimes it may happen when you remove both copies of your files and need to retrieve them back. Duplicate File Remover Pro provides a special option to restore removed duplicate files.

To Retrieve duplicates, go to the Menu Bar → Duplicate → select Restore Removed Duplicates.
Here you can choose any date session and view which files were deleted on this date. If the files are in the Trash folder, you are able to restore them. Learn more >>

*Please note, that when you remove files by Duplicate File Remover Pro, the program moves them to the Trash. However, this option is changeable. That’s why you need to check it in the Preferences → Remove section → a point “Remove Duplicates permanently.”

Upgrading From Trial to the Full Version of Duplicate File Remover Pro

You can try Duplicate File Remover Pro for free using the Trial. The trial version provides unlimited usage of the app for 7 days. After 7 days you will need to purchase the app to be able to continue using it. Learn more >>

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