Well yea, it is 2 654cc rotors, but only in the same way a 2litre 4cyl is 4 500cc cylnders, if you get me, its not derived from 2 single rotor engines.

Just different types of engine. Each rotor housing can be seperated from each other, just like a head can be seperated from a block on a normal piston engine (well, apart from monoblocks).

Cant seperate the head on a Rotor cause it aint got one