Yeah, maybe I rushed the question, but you guys got the point. I was actually looking at the Erica Dual VCF evaluating a rather "simpler" filter but capable of being used also as a true dual filter processing two audio signal independently.
As always you guys gave me constructive comments and new ideas and ascpects to think about! :)
-- Pescasphere
The Morgasmatron gets my vote. I own one just for the sake of disclosure. It's nice to have two identical* multimode filters. On channel one you can add overdrive and channel two you can phase reverse. You definitely can use it on a stereo source and modulate each side slightly differently. It also has a convenient switch to operate on a single signal in series or parallel.
Each channel is also capable of self-oscillating and has multiple filter options. So it's a good all-around workhorse of a filter module.