Are you able to take the same efficient metamagic enhancement in different trees?  Some of the builds I"ve been looking at have indicated that this is done. 

E.g. Efficient Metamagic: Maximize (3) in Angel of Vengence
and
Efficient Metamagic:  Maximize (3) in Archmage?

Most of the planners and things I reference lock them out, but I'm not sure if this is accurate, if there is a "trick", or if they were just referring to taking Maximize and Empower in separate trees?

Thanks!