Thanks boa
I've decided to separate them for now by way of a divider down the middle of the enclosure, as suggested by the breeder.
If or when I try to reintroduce them, I'll make sure to have even more foliage and branches. Although there was a bit before, they both seemed to like the same corner of the enclosure.
The one which appeared to be getting dominated did do a damned good job of hiding in what foliage there was, last night, though. It took me about 10 minutes to find him, he was so well hidden! I was starting to think he'd somehow got out of the enclosure.