1) I saw a bundle that included one game I already owned, and returned the individual game, not realizing the price of the bundle was discounted and this wasn't necessary. Make this more clear somehow and you'll have fewer returns to process.
2) The current return policy disallows returns after playing a game for more than two hours. For one bundle, I loved a game and played it for more than two hours. Then I tried other games in the bundle and got motion sick, making me want to return the bundle, but could not because I had played other games for more than two hours. It would be better for the consumer to take this into account on the return policy for bundles.