VisiPics - VisiPics does more than just look for identical files, it goes beyond checksums to look for similar...
dupeGuru - dupeGuru is a tool for finding duplicate files on your computer.
AllDup - AllDup is a freeware tool for searching and removing file duplicates on your Windows computer.
Pixiple - Find images similar in pixel and/or metadata content
Czkawka - Multi functional app to find duplicates, empty folders, similar images etc.
Visual Similarity Duplicate Image Finder - Visual Similarity Duplicate Image Finder will find similar and duplicate photos. Organize photos easily - supports 300+ Image Formats Including RAW.