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A bit earlier the same person said "Public can be re-rolled for owning part of a collection." so in the end it's up to person giving away title to decide that. One of the rules say "Don't enter for games you already own" and according to it you can ask for a reroll if winner owns the base game but no dlc (and I remember some giveaways of Dungeon Defenders Collection stating they are only for people who do not own the game; or not so long ago Daedalic Super Bundle allowing up to 3 games owned).
Of course you CAN enter for dlc if you own the base game but you need to remember that if you win it might get a reroll (because some people just want to give someone a new game and/or simply don't want the base to be wasted; others just don't care whether you have 1 or 90% of the package)