I imagine many voted just to create the novelty result, without any real regard for whether or not they actually, personally, liked either of the “princes”. One only has to remember their own high school days to realize how much, and how easily, students that age manufacture, join or become part of a “causes”, even trivial and silly ones.
It's likely that not a few of the students voted for the homos purely for comedy purposes, too. For let's face facts, ladies and gents: the homecoming king and queen "tradition" is downright gay, anyways.