VisiPics - VisiPics does more than just look for identical files, it goes beyond checksums to look for similar...
Powerphotos - PowerPhotos lets you organize your Photos libraries on the Mac. You can split a library into smaller ones, merge libraries together, find duplicate photos, and more.
dupeGuru - dupeGuru is a tool for finding duplicate files on your computer.
Monument Backup and Organization Device - Effortlessly store and manage all of your photos.
Duplicate Cleaner - Duplicate Cleaner: the fastest and most popular tool for finding duplicate files. Over 1 million downloads: Get your copy now! Free and Pro versions available.
digiKam - Professional Photo Management with the Power of Open Source