Both of those MIMO cards use the same chipset (Atheros AR5005VL) and therefore the same driver. I'd suspect the issue is with the driver itself, try using a reference Atheros driver for both cards and see if that works.
There is a reference driver available at
http://www.funchords.com/Atheros_4.1.2.71.zip although I don't know if it supports the AR5005VL.