Bob has a network and it keeps saving duplicate images. Leo says there's a lot of duplicate elimination programs. Here's a great article on Lifehacker. This article from Tech Republic could also help.
De-duplication is risky because he could get rid of the wrong file. Server 2012 has built in de-duplication. Duplicate Cleaner is a good option because it has a "hash" which shows which file is which so he doesn't delete the wrong file.