DupeCheck - a Mac OS X droplet to identify potential duplicate files
Created with Platypus
Based on this hint on macosxhints.com which contains the history & source of the underlying script. Thanks again to the bash gurus there who vastly improved my original script.
download, unzip, & stick DupeCheck on your Desktop (or wherever).
Drop a file on it and it will use your Spotlight index to see if you have a potential duplicate somewhere.
Released under the GPL.
Icon made with The Gimp