Med school applicants sometimes worry about adversely affecting their chances of admission because they might "offend" one school by applying to others. Good news: Schools will never know which other institutions or how many other institutions you applied to through AMCAS.
In February, med schools at which you are accepted will be able to access a report which will show them at which other schools you are holding acceptances. But, of course, at that point, it's too late for that information to harm you.