Duplicate File Finder
Having two copies of the same file doubles the space they take up on your hard drive, and adds a dash of confusion. Duplicate File Finder locates duplicate files and folders on all drives and removable devices. This utility lets you compare and preview graphics, HTML, text, and other types of files. It also tells you how much space you'd free up by deleting the dupes.
Duplicate File Finder also lets you add search filters--something many duplicate finders don't allow. You can speed up your searches by pointing it at only the likely target folders, and protect your data by excluding important folders from your searches.
Note: Please read the program's Usage notes at http://www.funduc.com/dupfiles_info.htm before using. The program has no internal decision-making to tell you what is safe to delete or not. You have to make that decision based on your knowledge and experience. If you're in doubt, do not delete the file. Take the the time to examine the folders where each set of duplicates reside and look for hard drive wasters, such as duplicate videos or image files. If one of the two files is located in the Windows folder, or any of the Windows sub-folders, I leave it alone.