Using 10.10 64-bit, though that shouldn't matter for this.

I have a netbook with a built-in T-Mobile GSM device that I pay for. I also have an AT&T USBConnect Lightening provided by work.

Both devices are seen by Network Manager and have been configured. However, when I attempt to connect using the AT&T device by clicking on that connection in Network Manager, it attempts to connect using the internal T-Mobile device.

I can see the T-Mobile device on ttyUSB0 and the AT&T device is on ttyUSB2.

Obviously, for one of these devices the port assignment is dynamic so where does Network Manager get this information, and where does it store it?