Just send one amp to a path output, and assign that output to USB 1/2, and the other path to a different path output and assign it to USB 3/4. If you haven't modified your unit global configuration you'll have your DI in USB 7. In your DAW you'll just have to select USB 1 (mono) or USB 1/2 (stereo) as the input for one amp track, USB 3 o 3/4 for the other amp track, and USB 7 (mono) for the DI track.
In order to monitor while recording, you will also have to send both amps to the 1/4' jack or XLR outputs, I use volume blocks to control the blend of both amps.
Dual Amp.hlx