An excellent program for finding duplicate files of all kinds is Auslogic Duplicate Finder. It's free and simple to use. Be aware that it will also find duplicates within other programs or within widows. Use caution if you try deleting these, as you could cripple a program or your computer. Limiting your search in Auslogic Duplicate Finder is very easy and flexible in their Option menu. Searching only for photos will do your work and keep you safe. You can find it in CNET's Download section.