Maybe I said this wrong.
How about Triple Stator with duel Rotors.
A main stator with rotor each side then a stator outside of each rotor to use the magnets power on the backside of the rotors.
I believe this is what I am asking about?
First: You want the stator between two rotors (consisting of magnets on a disk of magnetic material to "connect" the poles on the sides of the magnets opposite the coils). You want a strong magnetic field through the stator. If you put the magnets between two stators, without another layer of magnets and rotors to "complete the circuit" for the magnetic field, your magnetic field circuit is completed through air. Air has a relative (to vacuum) permeability of almost exactly 1. Iron, steels, etc. (depending on type) have relative permeabilities in the several thousand to several tens of thousands range. Build your sandwich with the magnets between the coils and the ends open, and you've increased your air-gap from fractions of an inch to feet. You drastically cut your mag field, and thus your output voltage.
Second: To get the most out of a given amount of magnet material, you want the gap between the magnets (in which the copper sits) to be about as thick as the sum of the thickness of the two magnets that are facing each other and creating the field through the coil. Starting from a thin set of coils and a small gap, as you add more copper, thicken the coils, and move the magnets apart to make room, you add generation from more copper more than you lose generation from less mag field due to the larger gap. But that flattens out, then turns down. When your coils are thick you gain less generation from adding still more copper than you lose to weakened mag field from increased gap. The maximum (assuming the mechanical clearance gap is zero) is with the thicknesses equal. (But it's not too critical, because the curve is horizontal at the max and gradually turns down going away from it. So you can go tens of percent, and goof around with some clearance between the coils and the poles, without substantial loss of power.)
Third: If you want to stack two stators with a double-sided magnet rotor between them and a single-sided magnet rotor on each end face of the sandwich, that works. But to keep the field up in the gaps you need the magnets in the middle to be twice as thick as the ones on the ends. So you might as well put steel disks across the middle of those magnets. (The field at the poles would be unchanged, because it's not going sideways to adjacent magnets.) But then you can split the magnets at the central disks, move the disks apart on the shaft (now the field DOES go through the disks to the back of the sideways-adjacent magnet, rather than through the disk to the along-the-axis-adjacent magnet) but the field at the poles is STILL unchanged (if the central disks are thick enough to carry the field well). Now you have two completely separate generators stacked along the same shaft, with exactly the same performance as if you had the double-thick magnets in the middle supported by a plastic disk. You end up using the same amount of magnet material and copper, which are your big costs.
Fourth: If you stack two generators you get twice the power. But if you use the same coils and magnets to make a SINGLE generator with twice the poles and twice the radius, you get FOUR times the power from the same magnets and coils at the same RPM (and four times the torque). You get one doubling from having twice as many magnets and coils (doubling the current or the voltage depending on how you wired them), and another from cycling twice as fast due to the poles being passed by twice as many magnets per shaft turn (doubling the voltage again).
Keep it simple and you get more out of it.
An UP side to building two genies is that if one fails (in a way that doesn't stop the other) the other may still be working, giving you power, while you're fixing the fried one. That convenience may be worth getting half as much power from a given amount of magnet material.
