Yeah, it must have something to do with the terms. Since you already purchased the game at X price or promotion, allowing you to repurchase the same game at a different price might make it easier to claim you only owe just the lowest price, or something else dastardly. You're buying the game, plus 3 gift copies, and to the developer the gift copies are worth marginally less, and thus selling 4 gift copies is basically giving the game away at that much less. The purchaser becomes a distributor, and could easily charge for the sale of gifting excess games purchased in bulk. It's the same reason you can't buy two 4 packs on one account. It makes sense, but now I'm just going to buy one copy for my girlfriend instead of 4 copies for her and a few mutual friends that would come play with us and make the game that much more fun.
If anyone ends up getting the 4 pack and wants to get rid of 3 copies, I'll paypal the difference.
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