They appear to be using both Donny and Liz through the whole dual tag. Clothes also look like Donny's.
I just noticed in this scan, at the screenshot with the dialogue You Win!, there is a lightly armored Lance user alongside the magic user. Do you think its promoted Donnie, a Halbedier, or a dismounted Cavalier?
I just noticed that in dual tag, it has no mention of Liz's HP. Do you think both units share HP in dual tag and that's why Donny's appears so high? Would be WONDERFUL for training.