Absent of insisting on two entrees, there really aren't any rules. You can pick the time when you'd like your main course, and order whatever is on the a la carte menu in between, including drinks. If there's extra, you may even request more than one main course.

As to annoying them, I'm sure they're prepared for whatever requests you may have in F. Now, if you order like 5 meals, though they may accommodate you, you may be the subject of some internal jokes (all in good fun, nothing malicious) amongst the crew during the flight.