There's no replacing them!

While I'm pretty much over the joke of "May the Fourth", I will continue to acknowledge it. It's odd that I didn't hear it at all for the first 25 years or so, and then couldn't get away from it. Also, I think "Revenge of the Si(x)th" makes more sense than "Revenge of the Fifth", with the side benefit of leaving Cinco de Mayo alone.

As for the problem above there is a 1 in 5 chance of selecting the correct protocol droid and a 1 in 4 chance of selected the correct astromech, meaning that there is only a 1 in 20 chance of selecting the pair of droids you're looking for.