If you test "on contingency," you forfeit the higher-level test fees unless you pass the pre-requisite tests. Be completely certain that you'll pass before you sign up to test on contingency.
Most clubs will only allow one contingency test because they have to block out and pay for the ice time, regardless of whether or not you pass the pre-requisites. If you registered to take Pre-Bronze Moves and Pre-Bronze FS at the same session, the freeskate test is already on contingency, so they may not allow you to register for Bronze Moves. (Check the announcement or registration form/site.)
There have been skaters who've taken multiple contingency tests, but those were arranged in advance with the skating club and judges, not just walking in off the street, so to speak. I know someone who took all her Moves tests in two sessions, but she was a coach who already had her Golds in Figures, Freeskate and Dance.