[SOLVED] backing up according to largest same file, software to check that or??

is there anything out there in software land that checks against a dup file size, if larger then move it on top of it to takes its place, or do I need to write a script for that?

(to satisfy the curious, I got a bunch of dups, I've been just copying over, or moving now that I am doing it again I am noticing zero file size one some of them. where I'd like to get the largest file size. which would best indicate a complete file, then move that one onto a hdd for safe keeping.)