I have like every DLC possible for Dynasty Warriors 7 and Xtreme Legends... I don't know if I have actually skipped downloading any of it after purchasing (been buying it for months now). Is there like a list anywhere on the ps3 saying what you have? It seems I can keep downloading the same things and it never says if I actually already have it downloaded.
As far as I know there's no easy way to see if you have the dlc downloaded or not (Been wanting a way myself) but to enter the affected game to check if you can see it somewhere in the menus there. Otherwise you might just have to download it again just to make sure, unless you have some download limit (Weird concept that I find hard to grasp, guess I'm too used to having no download limits).