I don't think it is 100% the same. There must be something different somewhere.
On BFGMiner with the current driver the current hash rate is show at half the speed it is running at. On the same hand the effective speed shows up properly.
I have tried it on 2 different systems with the same results.
Maybe the problem is that the firmware version string still reports "2 chips", but when it submits results, it provides a chip number 0 through 5. That's the only thing I can think of that would be different between the devices.