They could track it if they really wanted, but don't go trying to skirt the limit. That's what ruins good deals like this.
Actually it's because i'm trying to buy these with a friend but since i don't have a card active at the moment then i'm screwed, so i wanted to see if my friend could buy two with his amazon account, and another one by using his brother's amazon account which has the same credit card as my friend's account.