The CS-80V is not a common multitimbral synthesizer, I mean you can't have one preset for channel1 and an other for channel 2. But you can choose a particular channel to trigg a particualr voice, and on each voice you can have a particualr sound.
Open a CS-80V in cubase.
Select 2 midi track. Select the CS-80V(1) channel 1 for the first, and CS-80V(1) channel 2 for the second
On the CS-80V :
At the left of the multimod panel, you have four row z1,z2,z3,z4. This are four midi selection zone.
select channel 1 for z1, and channel 2 for z2.
On each voice you have a midi selection window (ZONE). Select 1 for the voices 1-2-3-4 and 2 for the voices 5-6-7-8.
Then for each voices, you can choose a different patch.