From my understanding of the EMV payment specification (http://en.wikipedia.org/wiki/EMV) a card can actually have multiple applications and when used at a compliant terminal, you are prompted to select the payment application. In other words, a EMV compliant terminal should prompt you to select which card you want the charge to go to. Of course this isn't a terminal behavior you typically see because pretty much any card you get issued by the bank will only have the one payment app. In my own testing though, I've come across cards with more than one.