MOTM

>Or, turn it into a feature and set up slightly different voices on purpose.
>Can be slightly different settings on identical numbers, can even be
>using different modules, like Moog VCF on one voice, 2040 VCF on
>next voice ...

This is what I usually do. I have enough VCOs, VCAs, LFOs, and EGs to 
create some nice four voice patches. But I don't have four of any one 
filter, so I just use different ones on different voices. Makes for 
some interesting sounds.