

Once it gives you a list of found duplicates, you can select them all, choose "View in new window", then click on the new window to slideshow the images.Choose the folder where you want to search for duplicates (you can select a top-level folder and scan recursively), then choose Compare by Similarity (or Similarity - High).

However I found out its behavior to be a bit strange and thus Digikam is better (also, it's not possible to view easily found duplicates to confirm them, which is very problematic, and Digikam does that very well). A tool that can work as well is Geeqie (in Portage).A collection (or root folder) has several albums and is configured via Settings -> Configure Digikam. Be careful that an album is not the same as a collection.

Also it seems to create a hidden (starting with a dot) folder in some directories, to implement trashes.
