@Kirukle:
There are no rules against being on multiple teams, in fact we've had a student on two teams who placed in both!
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. It'd be a violation of the spirit of the rule to have the same team enter the contest with two different rules (and I would hope that their advisor would say "we're not gonna do that here").
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.