Duplicate Cleaner Keeps Your Hard Drive Clean

"Unlike a number of apps that promise to help you clean duplicate files from your system, Duplicate Cleaner can scan files for content, not just by filename. You can customize a wide range of filters when performing a duplicate search, and choose to limit your search only to images and pictures, music, movies, text or Office documents, or just scan entire drives.

Additionally, you can tell Duplicate Cleaner to scan for content, or restrict its search to filename, file size, or creation date. You can even specify a range of file sizes to filter search results on, so if two files have the same name but are vastly different in size, Duplicate Cleaner will ignore them."

http://www.appscout.com/2008/09/duplicate_checker_keeps_your_h.php