If I understand his question correctly (as seen through the eyes of a newbie); and frontpage32 can correct me if I am wrong, he is asking if a dual stator gen. can be combined and used at the same time. I believe Flux answered it quite simply. Two stators wired differently can not be connected at the same time, as each will be producing differing outputs. An analogy to that would be to have a vehicle with one wheel geared for speed, and one for torque, and wanting to use both at the same time. Each one has merits of its own, on its own.
And regarding using larger rotors, more magnets, and more coils per stator, as before, the explanation is spot on. But I seem to recall someone comment (perhaps another forum) that they had several stators sitting around. I don't want to risk hijacking the thread, so i will only suggest that if you wanted to research further on multi-stator, start and stick with 'like-wired' stators. You could wire them in series to increase your voltage, or in parallel to increase your watts.
If this were an existing machine you were to modify, you would be doubling the "work" you are giving the blades. And as all parts of a machine affect each other, you would be inclined to do things like increase the swept area, etc... but modifying an existing machine in this way seems unlikely.
Thanks for the dumb question, and keep them coming. I'll try to provide my share. The things in life I learned the most from were my biggest mistakes. And I have two older brother, who provided me with a wealth of wisdom.