Delete Duplicate Files on External Hard Drive on PC and Mac: Steps and Tips

Summary

The easiest way to find and delete duplicate files on an external hard drive is to use Cisdem Duplicate Finder due to automatic duplicate detection and quick, reliable duplicate removal. 

1. Download. Download and install Cisdem Duplicate Finder.
2. Scan. Use this app to scan your external hard drive or specific folders on it.
3. View. View duplicate files found by the scan.
4. Select. This app automatically selects all duplicates for deletion and lets you make adjustments.
5. Delete. Click Delete to remove all selected files and confirm the removal.

All duplicates are now deleted, and the original files are kept.

Free Download Windows 11/10/8/7 Free Download macOS 10.11 or later

 

 

External hard drives can be used for backing up files, transferring files between computers, or other purposes. During usage, duplicate files are likely to accumulate. By deleting duplicate files, you can free up space and potentially speed up your external hard drive.

In this article, I will share two different methods on how to remove duplicate photos, videos and other files from an external hard drive on Windows PC and Mac.

How to remove duplicate files from your external hard drive automatically

This method applies to both Windows and Mac and uses an app called Cisdem Duplicate Finder. Compared to the manual method (which is time-consuming and can’t ensure accuracy), this method is much, much easier, faster, and more accurate.

Let’s take a closer look at why Cisdem Duplicate Finder can be so helpful.

• Use advanced algorithms to accurately scan for duplicates in all file types (such as photos, videos, and audio files) by content and even find duplicate files with different names
• Scan 9.27 GB of files in just 11 seconds
• Scan your entire external hard drive, specific folders on it, or even a Photos library on it (for Mac users)
• Allow you to view duplicate files before removing them, letting you make informed decisions
• Take just a few clicks to remove all duplicates, leaving original files untouched
• Support any external hard drives, regardless of types (such as HDD or SSD) or brands (such as Western Digital or SanDisk), as long as you can access and manage the drive properly on your computer

Steps

Step 1: Download the duplicate file finder

Download and install Cisdem Duplicate Finder on your Windows or Mac computer. Open the app.

Free Download Windows 11/10/8/7 Free Download macOS 10.11 or later

Step 2: Add your external hard drive to scan

Connect your external hard drive to your computer. Click the Add button to add the entire drive or specifics folder on it. Click the Scan button to find duplicate files.

Step 3: View found duplicate files

After the app finishes scanning, you will see the results window. The All tab displays all found duplicate files, and other tabs (such as Image) lets you view duplicates by type.

If needed, you can change the view mode, search results by name, and sort results by name or size.

Step 4: Select duplicates for deletion

In each group of duplicate files, Cisdem Duplicate Finder automatically selects the duplicate(s) for deletion, leaving the original file unselected.

In other words, all duplicates are selected for you to delete at once, and all the original files are unaffected.

Also, you have the flexibility to select or deselect files by hand or choose a desired selection rule.

Step 5: Remove all duplicates at once

Once you are sure that all unwanted duplicates are selected, click the Delete button, then confirm the deletion by clicking Yes in the message that appears.

I also made a video tutorial to guide you through this entire process.

Tips

Tip 1. Protect your important folders and files

It's likely that your external hard drive has some important data that you want to keep untouched. You can easily protect them! Before clicking Scan in step 2, go to Settings to add your important folders and files that you don't want to scan to the Ignore list, such as your backups.

Tip 2. Speed up scanning and improve efficiency

Cisdem Duplicate Finder, with its default settings, scanned my external hard drive containing 9.27 GB of files in 58 seconds. The speed was increased (11 seconds) after some configurations. Below is how I configured settings, and you can adjust them based on your needs.

• Turn off Enable similar images function: I turn off the feature that finds similar photos, which greatly increased the speed.
• Select minimum and maximum file size: I excluded files smaller than 1 MB from scanning since I didn't care about small duplicates.
• Ignore folders and files: I ignored two backup folders. (Yes, ignoring folders also helps speed up scanning.)
• Ignore scanning file formats: I also ignored all MP3 files because I knew there weren't duplicate MP3 files.

Tip 3. Effectively delete duplicate photos on your external hard drive

Technically, duplicate photos are exactly identical, regardless of their names. However, some people may also consider similar photos as “duplicates”. If you want to handle these on your external hard drive, make sure Enable similar images function is selected in Settings.

Tip 4. Remove duplicates from your Photos library stored on an external drive (Mac)

If you are a Mac user in this situation, extra actions may be required to complete step 2.

1. Double-click your Photos library directly on your external hard drive, which will open the library in the Photos app.
2. In the Photos app settings, click the Use as System Photo Library button. (Ignore this tip if this button appears gray, which means the library is already the system one.)
3. Now you can add the Photos library and click the Scan button.

 

How to find duplicate files by hand on your external hard drive

If there aren’t many files on your external hard drive, there’s an alternative method, with which you look for and eliminate duplicates by hand. This manual method takes time and is not efficient, but it’s not infeasible with a small number of files.

The method requires the use of the built-in file manager on your computer: File Explorer (Windows) or Finder (Mac). Alternatively, if you have installed file manager app (such as SanDisk Memory Zone) from the developer of your external hard drive, you can use that.

Use File Explorer (Windows)

Here’s how to find duplicate photos on your external hard drive and delete them with the help of File Explorer.

Step 1: Connect your external hard drive to your computer.

Step 2: Open File Explorer, find the drive in the Navigation pane on the left, and open it.

Step 3: Filter photos by typing kind:=picture in the search bar in the top right corner. Now the File Explorer window only displays all photo files stored on your drive.

Step 4: Select View > Details, then select Sort > Group by > Name (or Size). Now it becomes easier for you to discover photos with the same name or size, which are potentially duplicates.

Step 5: Go through photos to find duplicates by comparing their contents, names and sizes. Right-click the duplicates that you have found and select Delete to move them to the Recycle Bin.

Continue handling other types of duplicates in a similar way.

Use Finder (Mac)

Follow the steps to use Finder to look for duplicate files on your external hard drive and clean them up.

Step 1: Connect your external hard drive to your Mac.

Step 2: Open Finder, find the drive in the sidebar on the left, and open it.

Step 3: Filter photos on the drive.

• Press Command + F to bring up the advanced search in Finder.
• In the first drop down menu, choose Kind. Then choose the Image file type from the dropdown menu. You can further choose a specific image format (such as JPG) if needed.
• Now the Finder window only lists all photos stored on your drive.

Step 4: Experiment with different sort orders and view modes until it becomes easier for you to spot potential duplicates.

Step 5: Manually identifying duplicates by closely comparing photos. Select the unwanted duplicates, control-click, and then choose Move to Trash.

Now you can handle another type of duplicates in a similar manner.

 

Conclusion

Why do you have duplicate files on your external hard drive? There can be various reasons. For example, duplicates already existed in the files that you backed up to the drive. Moving files by copying and pasting instead of using drag and drop also creates duplicates.

Luckily, you can easily remove those duplicate files from your external hard drive by using software. The process is easy and quick and lets you rest assured that duplicates are correctly identified and safely deleted.

In addition to regularly cleaning up duplicates, you can try preventing them from appearing in the first place, such as by avoiding necessary backups, using drag and drop, or naming your files in a logical way.