To find duplicates items on an external drive, please follow the steps below:
1. Launch PhotosDuplicateCleaner.
2. From the menu, click on PhotosDuplicateCleaner > Preferences option.
3. A new window "General" will open. Here, you will see a list of directories under "Ignore directories with names:" option.
4. From this list, select "Volumes" and click on the "-" symbol to remove this directory from the list.
Now, you will be able to scan the external drive for duplicate items.
If you still face any problems, you can contact our support team at firstname.lastname@example.org
with your query.