Squeak ,I think you are confusing osillators with partials[partials being a tone that is layered or velocity switched].The MZ 2000 is 64 voice, and most of the good patches are reduced to 32 voice polyphony..

Osillators are combined to make a tone..
Rolands JV/XV are simular..4 tones make a patch..You can additionally combine patches though on the Roland structure..Likewise with Korg[combine]..