The only way to be *absolutely* as close to certain that you will be in the same league that I know of is to a) have no other facebook friends that play T11 (this is important) and b) have one start the game as a new player and invite the other in and the other follow the invite link to start the game,having *never* started it before on that facebook.

The easiest way to do this is each of you start FB accounts only for the game.