Double depositing is VERY very common and taken for granted at most public universities since students get their replies between August and January, and use that to save a spot and make sure they have housing. Universities often even refund the deposit, although not always. However on May first students must say where they’re going and GC 's will only send ONE transcript to the one school selected as the final choice. Students on waitlists can withdraw their decision to accept their place at the school where they got off the waitlist.
The 'double deposit ’ rules in the link above apply to double depositing AFTER May first.