Your youngest will have the advantage of seeing your older son get into wherever (possibly not first choice), deal with it, and then go off and (hopefully, most likely) THRIVE. That’s a huge gift of being a younger sibling, seeing that it all really does work out OK and the vast majority of students end up happy!
It sounds like you are doing the perfect thing which is to use careful language and expectations around the process at home. Sounds like your sons may have some pressure at their school, but you can (and it sounds like you are) counteract that at home.
Also remember that this is a small but intense window of time (applications/decisions), and then you shift into the fun part of looking forward to and preparing for college…and your younger son will get to observe that process as well!