If they have one strike on display showing the logo side as long as the strike you win has that logo it's yours regardless of what the other side shows and I don't think one would have much of an argument that it is an old strike.

If you win a strike that has a different logo and not on display on the other side I am fairly sure you would win any contest with the casino or Gaming. I could only imagine putting money in a vending machine that only displayed Snickers and M&M's and a Tootsie Roll coming out and them telling you that is what you must take.

Of course some casinos have put a sign on the machines saying that the strike you win may not be on display.