Hi,
Check these out
http://windows.microsoft.com/en-US/windows-vista/Eliminate-duplicate-files
Here are several free utilities and they all have their advantages and methods.
Auslogics Duplicate File Finder has the MD5 search engine which allows you to find duplicate files by content,
regardless other match criteria. It would be helpful, for example, when two identical mp3 tracks or video files
have different names
http://www.auslogics.com/en/software/duplicate-file-finder
find and remove duplicate files - free
http://www.easyduplicatefinder.com/
Installer and Portable versions
searches for duplicate or similar files - even binary - free
http://www.joerg-rosenthal.com/en/antitwin/
find fast all duplicate files in a folder and its sub folders - free
http://www.mindgems.com/products/Fast-Duplicate-File-Finder/Fast-Duplicate-File-Finder-About.htm
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Duplicate File Finder Software (images, mp3, iTunes)
Hope these help.