1 question

You tell the creator of one to reroll.

Then you are one lucky bastard. I would love to win 2 copies of a game in a row :D

Don't accept it. If you already have, don't activate it. Give it back to the creator so it can be re-rolled.

Any other course of action will most probably lead to a suspension...

Does your question fit in the thread title?

Say thanks, ask for a reroll and move on.

There used to be a thing called "Common Sense", that's what I used to rely on, seems to be more of a myth these days.

Decline one of the gifts and ask the contributor to re-roll their giveaway. Same thing happened to me as two giveaways ended within 17 minutes of eachother and I won both.

take the first, tell the second one to reroll...

is't it if you won them both within 15 minutes its not your fault?