Wheatstone actually patented such a system in the 1840's. (Fourth claim on p.9, and in figure 13 of the 1844 patent-- see http://www.concertina.com/wheatstone/Wheat...041-of-1844.pdf ) I've been thinking and drawing and plotting how to use a variant to produce a single reeded, but bisonoric (same note from same reed on push and pull) bass. I even went so far as to buy a set of organ reeds to experiment with. Early Wheatstone basses seem to have used harmonium reeds, so my idea doesn't seem too far fetched. My designs need four valves per note. I'm not sure that the channel construction is significantly more complex than the usual reed pan+action board.
I have been thinking about the same matter, some reed organs were operated by push and/or draw wind, they were rather complex in their construction. Is it not possible to use idioglottic reeds as in the sheng? Concerning the keyboard lay out would a B or C Griff as a lay out for duet concertinas make sense? Because one plays a concertina just for the sound of it, not for the complexity of the system!