This is a double-question where the expected answer is still a question. That is, the *real* question word in {SaH'a' 'Iv} in context is {'Iv}. There's no confusion about whether you're supposed to answer a "yes/no" question, or a "who" question, because the context determines that the asker is trying to clarify to whom the first question was asked. The {-'a'} is actually expected to be part of the answer and so isn't really serving as a question word here.

As for something like {nuq legh 'Iv}, asking for two pieces of information simultaneously, I don't see why not. For example, if Horatio is related excitedly to Hamlet how Marcellus and Bernardo saw his father the king's ghost, Hamlet may very well excitedly ask {nuq legh 'Iv jay'?!}

I can't say whether Klingon grammarians would approve of either, but both seem like the sort of thing that might happen naturally in conversation and be understood, proper grammar be damned.