My hunch is that the 21.0 will not do "UHF Band A" - only "UHF Band B". I'm not sure how that affects your situation.
I would suggest setting up the 722 using the old remotes to have TV1 be UHF Band B on one channel, and TV2 be UHF Band B on a different channel, and then setup the remotes to match those channels (which can be done without a Dish receiver).
I would suggest setting up the 722 using the old remotes to have TV1 be UHF Band B on one channel, and TV2 be UHF Band B on a different channel, and then setup the remotes to match those channels (which can be done without a Dish receiver).