Duplicate finder will only show date created, but not last saved. Creation date is useless when you want to make sure your not deleting the latest file(s).
That's correct; typically, for many of our users, that would be the desired information, since the files they're looking for wouldn't be altered after creation. (For instance, photos in the Pictures library.) As such, finding out which one was created earlier would be more useful in this use case.
I'll let our design team know about your concern with this display, however.