Hmmm, that surprises me, as I saw this online:
http://www.everythingusb.com/asus-varidrive-21718.html
" Its video processor can drive up to two displays at resolution up to 2048 by 1152 (16:9)"
That certainly seems to imply that it can drive two displays at once.
Is this a hardware issue or a displaylink compatibility issue? Or is it simply that USB 3.0 is not fast enough to send information to 2 displays?