Just a thought, and I don't of course know which independent school you are applying to, but it may be that the school is trying to gauge realistically how many places to offer. When we applied to two indies last year, I was quite open in the interview with the Heads that we would take up a grammar school place if successful; my DS was still subsequently offered scholarships by both indie schools.
Good luck in whatever you decide.
Quite likely that this is the case - I suspect that the schools may genuinely be getting info - not actually being judgmental. However difficult for the kids in stressful situation. easier if they already have some results!
I was interviewed for second choice Uni - I was asked if I had been interviewed elsewehere, said that I had unconditional offer for X - th first choice - guffaws round panel ... "if you've got a place there - you won't want to come here will you?" ... superconfidence of the 18 year old comes out and replies that it would be nice to have the choice! Another equal offer arrived...