Suggestion: Reroll when the winner has already owned the game.

This is in response to the thread by Dyna
http://www.steamgifts.com/discussion/aES6B/suggestion-remove-people-automaticly-from-giveaways-when-they-win-or-buy-the-game
that suggests people to be removed from existing giveaway when they win a game.

From a implementation stand-point I think that could be a little computational intensive because the system has to loop over all the participated giveaways. (Also there are other implications stated in that thread).

If the aim is to reduce the workload of the support staff (from rerolling), I think a simple work around is to perform automatic reroll when the winner already has the game in his/her steam library (the system need to force sync first). This would fix the following problem:

1) Winners redeemed the gift but did not remove themselves from other giveaways of the same game.
2) Winners bought the game after joining a giveaway.

However, this would not fix the problem when a winner won a game simultaneously, but my intuition tells me the chance of that happening is pretty low.

tl;dr: when a winner won a game, do a force sync and reroll if he/she already own the game.

Disclaimer: The main idea is from Dyna from the thread above, my suggestion is to perform the check whenever a winner won something, instead of looping through all his/her existing giveaway.