Visipic is a program that is considerably faster than any other commercial product and has an interface that let you do other things while Visipics automatically finds your duplicated images. It will detect two different resolution files of the same picture as a duplicate, or the same picture saved in different formats, or duplicates where only minor cosmetic changes have taken place.
All detected duplicates are shown side by side with pertinent information such as file name, type and size being displayed. Its auto-select mode let you choose if you want to keep the higher resolution picture, space-saving filetype, smaller filesize or all of the above. If you are insecure over what you really want to delete you can manually select the images you don't want to keep and delete them yourself.