Maybe noob question, but...

Can I enter DLC giveaway even if I already own it?

Yes I have read FAQ, but rule only states "Don't enter for games you already own."

By "games," do they also mean DLC? Or just regular games?

Not only that, but also once I synced account, I CAN'T enter giveaway for game I already own, but for DLC, I still could, ever if I already own DLC?

So... can I enter for DLC I already own?

EDIT:
Ok, so the answer is NO...

But yet I'm sure in history, there is hundred of users won DLC they already own, then do something with it, like give it to friend or whether. Steamgifts should do something about it, just saying lol.