Korg 800DV question

[Haible Juergen]

Hi,

I was wondering if anybody knows how the keyboard in
the Maxikorg (800 DV) works.
It is said to be a duophonic version of the MiniKorg (700),
and the 700 has a similar resistor ladder as the MS-20
for a direct exponential CV output (V/Hz.) I think this
is a brilliant design, only using a couple of different
resistor values, but I cannot imagine how they could make
it duophonic. 
Schematics for the 800DV, anybody ??

Thanks in advance,

JH.