Backtrack:  
 
by lunarg on March 29th 2017, at 11:42

Duplicate Files Finder is a fast application which checks duplicate files by comparing its file sizes. Because of the method it uses, it is extremely fast but not very accurate. It is available for Windows only.

dupeGuru is more specialized application for finding duplicate files as it compares by contents as well. It is primarily available for Linux and Mac OSX but although no longer developed for Windows, you can download an older version of the program for use on Windows.