Usually if that is the case, you ask for another interview while you are still there for interview day. Some schools will give you another interview with a different faculty. I personally wouldn't think they look upon this very highly.
Even if you don;t think it went well, I've heard from a bunch of people that they have gottne accepted to schools where they had these stress interviews and felt they didn't do well... So it's hard to judge interviews. So unless there was something extremely wrong, i wouldn't sweat it... But if you do feel it went horrible, you could call the admissions and ask them if there is anything you can do.