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It does sound as though they're being a bit cage territorial, I have to admit I've never had a pair so I'm not quite sure how you deal with it if both are trying to bite!
I've found none of my russians seemed to like being in a plastic bin & found a play pen with lots of toys, a wheel (or two with a pair!) some substrate from the cage to make it familiar works better & they soon get to enjoy that, it makes it easier to interact with them too as you don't have to approach from above.