Help needed with winning an already owned game

I didn't know this page existed! Btw the support was super nice and said there's no problem at all, they contacted the GA creator and they'll sort things out

C'mon, we're talking about one of the best communities in the internet, I already feel kinda bad for being mostly a leech and having won much more games than I gifted. I'd like to think that nobody would do something like that :(

Oh ok, didn't know that. Then it's possible that it's the fact that it's a "deluze edition"

and (some?) packages/subs

Any package/sub which includes at least one DLC, since the issue similarly relates to Steam not being able to send out DLC ownership data.
There's also a couple of other much rarer bugs- one involving the fact that DLCs which require other DLCs can obviously not have the prerequisite ownership verified by SG (as an extension of the first issue) causing the giveaways to be unable to be entered, one involving older "expansion" configurations on Steam (which happen so rarely that I've forgotten the details, but iirc they're treated as both a base game and a DLC, causing the weird issue where SG wants to check for prerequisite ownership but also can't properly do it), and the fact that publishers may misconfigure packages so they misreport their contents (typically meaning all a GOTY reports is the base game, which SG takes to mean that anyone with the base game owns all content).

Generally speaking, all one has to worry about is checking if a DLC is involved (namely, since all the other issues lock out entry entirely). If one is prone to such oversights, then [while signed into Steam Community] just clicking on the game image in the top left of any giveaway to verify you don't own it before entering is always a good step to take, if keeping your SG ignore list regularly updated as your library increases isn't workable.