Most people that I've encountered take the MCAT twice. There is no set policy on how it is viewed, it depends on the school. Some average the scores, some only look at the highest scores. If you're interested in a particular school you could call them up and see if they can provide you with more info. If you can avoid taking it more than once that's great, it's a bear of an exam. But if you have to go for it a second time it's not the end of the world. In fact, a friend of mine took it 5 times before she finally got accepted to Albany.