When you search for a file name, and LW says there's multiple copies of it, how does LW know the files are identical. Is it based on the ascii text of the filename and maybe the file size ? Or is there some kind of long unique serial number secretly embedded into the file by LW at some stage ?

I'm asking because often I want to rename some files that I've downloaded but I don't want to mess up the effectiveness of other LW peers search results.