I got 3 dualminer2 today as well as a Gridseed.  I am able to get them all up and running (using different versions of cgminer for each) without any problems-- at least when testing to wafflepool, scryptguild and clevermining.   
I was actually trying to solomine an altcoin directly to a wallet-- I've got a GPU box doing that just fine (host:8332) to the exact same wallet however when I point either the gridseed or the dualminers at the wallet it connects and appears to be hashing away just fine except I never get any accepts or rejects.  The hashrates the cgminers report are reasonable yet no accepts.   
 The only thing I can think of that is different between mining to a multipool and a local wallet is that the local wallet is using http (getwork I believe) rather than stratum.  cgminer shouldn't have an issue mining to a wallet-- after all I use an unmodified cgminer on my GPU box with no problems also using http.   Anybody have any ideas why this isn't working?