A free program for Android, by Niam Technologies.

Duplicate Photos Cleaner App is a handy utility that is capable of locating and removing duplicates from your device. Duplicate Photos Cleaner App works in a very simple and easy-to-use manner.  It does so by scanning your device for all the images, videos, and other files that are present on your device and that are similar to one or more existing files. Once it finds a match, it will allow you to choose to delete the duplicate photos and videos or to keep them. This way, you can clear up storage while still making sure you have one more copy of a photo or file.