A question about a giveaway winner.

What happens if the winner never activates a received game?

My last giveaway gift was send minutes after it ended and it's been over a week and the winner has his inventory hidden and the game is not in his library.

I also noticed in the winners friends list he has a friend with the same Steam name and that friend has the game in his game library. It was just an assumption that he might have multiple accounts and he just sent the game to his main account. Is that allowed if true?