So the answer is actually the same for part a and part b?

Yes. The thing is, if the two have different answers, and the students know they are guaranteed to have different answers, then there's no point to asking the second question. So I make sure, this way, that the students know there's no guarantee. (I could have outright said that there's no guarantee, but then we get into I-know-that-he-knows-that-I-know territory.)