There are no rules against being on multiple teams, in fact we've had a student on two teams who placed in both! (that was the game competition, not film, but the rules are essentially the same)
Having said that: Our RECOMMENDATION is to not do that unless there's extenuating circumstances - the student above was in a game art class in one period and a game programming another period, so entered once in each class.
Ultimately it's up to the teams' advisor *BUT* our recommendation would be "no". An exception might be something like sound - there's not enough sound people in the class to put one on each team, but one sound person splits themself across a couple teams. IMHO in any other case the time would be better spent upgrading/polishing/etc the 'first' game rather than being part of two. There might be other extenuating circumstances and rather than AMES nitpicking every possible scenario we're recommending "no unless there's an extenuating circumstance" and we're going to accept whatever the team advisor deems "extenuating".