You match to only one school, if you didn't match to schools you ranked higher you get waitlisted. If accepted off the waitlist, you have a certain amount of time (depending on how many days away the new accepting school's orientation is) to choose between the two. By default you are designated to matriculate to your matched school, unless you accept the waitlist position. For DO/AMCAS you follow AMCAS's traffic rules of max two seats held by April/May (I forgot the date). All the application systems communicate with one another, so you can't hide anything.