I'm pretty sure that it asks you about the lowest-priority show. That is, if you don't want to cancel the lower priority show, then you probably don't want to cancel the higher-priority one, either. But I could be wrong. I've never done any tests.

That all works well on paper, but in reality, no one goes through and prioritizes the entire season pass list, and the priorities of those shows might be backwards since you never had to make a choice before.

I do know that it only asks you about one of the two shows, though. It definitely doesn't ask you which of the shows you'd like to cancel, or even tell you what the other show is. Fortunately, it's pretty easy to find out.