Give me the option of keeping duplicate files in another file instead of deleting.

I am involved in a large legal case and would hate to delete something that is important. At the same time, I am being overrun with duplicate files after years of working on it. I would like the ability to put the duplicate files in another file to zip, but have them just in case they really werent duplicates. I would like to know if even a period is missing.. and that should make it another file.