If you feel your hard drive has lots of duplicate files, Tidy Up can help you find and remove them permanently. This is a tool for Mac that uses multithreading technology to find duplicate files that meet whatever requirements you select.
Aside from files on the hard drive, Tidy Up also scans iPhoto pictures, iTunes songs, and saved emails.
To create the search parameters, you just have to check or uncheck the appropriate boxes. The sidebar shows you which parameters have been selected. If you create an effective set of search criteria to find a particular type of duplicate file, you can save and recover it whenever you need.
If the results yield a large number of files, Tidy Up can quickly organize them using smart boxes. If the file fits in the criteria of the smart box, it appears there.