I would personally rule that those two specific revelations could be chosen more than once, albeit only for a different maneuver or weapon each time. It wouldn't break anything at all, unlike taking (for example) Cinder Dance as many times as you want. Also, the language for those two revelations is a lot like the Weapon Focus feat -- "select one type of combat maneuver" or "select one weapon with which you are proficient," vs. "choose one type of weapon" -- so it seems pretty clearly allowable to me.
Call them Maneuver Mastery (Trip), Maneuver Mastery (Sunder), Weapon Mastery (Flail, heavy) and Weapon Mastery (Lucerne hammer) if you have to justify to yourself how they're different revelations, but they are. A rose by any other name, yadda yadda.