I used to work for GS, and yes, they totally track online sales data. They don't want to be suckers. When Disgaea started to rise early on (before all the reprints) they quickly went back and upped the price on used copies. In the case of your Pikmin 2, it probably just got overlooked in a price change. The second sticker on the side is just for inventory checks so the employee can scan the side of each box without having to slide each one out.