Here's a great duplicate finder software, but for photo's. It searches your database and matches the similar looking images. I must say it's some pretty impressive software to do that. And if you have copies of the same photo's, you can either remove them or file them for storage.
AntiDupl is a program that will organize your photo library one picture at a time.
Link
AntiDupl is a program that will organize your photo library one picture at a time.
Link