First of all I would like to say Hello to everyone on this forum. As to my question: Does anybody know of a duplicate file detection utility that can re-use MD5 values for future comparisons? Let me explain. Basically, I am trying to accomplish the following: 1) I have a "main folder" containing thousands of files. 2) I would like to scan this "main folder" only once and save all the MD5 hash values for future comparisons. 3) When I add new files to the "main folder", I would like to first check for duplicates against the MD5 values from step 2. I've seen lots of duplicate file search utilities but they all need to rescan all the folders each time you add new files, thus, taking a very long time. TIA