It was a joke. Did they also say double power-up points? If so, it's a joke.
If it's a joke, then I don't get it.  What's funny about it?  Where's the punchline?  It also says for Assassin's Creed Revelations you get an extended gameplay mission, a weapons capacity upgrade, and a multiplayer skin...  Haha?  Yeah... that's hilarious.
Also, what it says is "double power up rewards points", which I believe refers to some sort of redeemable points system that gamestop has.  They've given them to me when I've gotten other games from them in the past.