As someone who’s spent too much time over the years in interviews, I can tell you that it’s kind of shitty to ask questions of candidates that are not really any of your concern and that put the candidate on the spot with no good answer. You may think you’ll use the answer in a beneficial way, but that other company’s interviewer down the street may not. It’s not fair to put someone on the spot like that when the ball is so much in your court. Just assume by default that you’re not the only company the person is open to applying to. Don’t make them have to lie or withhold information (unless you really do need to know in order to make a timely offer).