Entered two giveaways for the same game, somehow won both. But I don't want both!

Just ask one of the creators to resquest a new giveaway =)
Edit: On SG I mean, in the GA comment section

You hsve to ask to thr creator of giveaway in thr comment to request
A reroll~

Post on the giveaway page that you don't want it and request they reroll. If the person still doesn't reroll just leave it alone. Eventually the unmarked result will get them to reroll.

Edit: Ninja'd, stupid damn slow internet day :/

Contact one of the GA creators , explain the situation and ask him to reroll .

Reply to the second giveaway, explain the situation, and request a reroll.

Comment on the second giveaway.
That error usually happens to me when you add and remove someone and then try to add them again
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First off, mark the key that you activated (and only that one) as "received".

Since you can't get hold of the creator of the other giveaway you can write a comment in the giveaway itself, quickly explaining that you won another giveaway for the same game at the same time, that you haven't used his key, and that that he should request a new winner. The giver can request a new winner and point to the comment that you made, which should be enough for support to approve the reroll.

It's rather awkward for the giver, because they can't be absolutely certain that you haven't used the key, but as long as you haven't then everything should run smoothly.

1. Activate the first win, and (assuming success) mark as Received
2. Add a comment in the second win: "I won this game from another giveaway. Please request a new winner. Thanks!"
3. Important: Do not mark the second giveaway as Received or as Not Received. Just forget about it, and of course do not activate or re-gift the key. For all intent it's not yours to use and should be assigned a new winner.
4. To reduce the chances of multiple wins in general, after winning, resync your account, go over your entries to other giveaways of the game you just won and remove them manually.
5. Bump this thread so that more people in the same situation know what to do :-)

Oh, geez, I didn't even realize you could leave a comment on a giveaway that's ended. Thanks, guys!

I thought this was a jab at the usual "I won two games" threads in an attempt to make a giveaway thread.