The Hamster Heaven is a great cage and it all sounds fine if you don't have the levels in and two wheels. I have seen a lot of people recommending one larger open wheel and one smaller one - it's easier for them to run together in a larger wheel. What wheels have you got at the moment? I think the HH comes with a small wheel already. An 8.5" comfort wheel or even an 11" open wheel could be good as an extra. The 8.5" comfort wheel isn't expensive, but depends if you want a quiet wheel or not!
They might settle if they've just moved. You could try scatter feeding as well as or instead of having food bowls - that also helps reduce territorial behaviour.
Maybe add another house as well - even if you have two of everything, sometimes a third thing helps or a house that's big enough for them to both fit in and has more than one entrance (so one can get out if the other blocks the door). A shoe box or tissue box can make a good house and just cut entrance holes where you want - maybe one at the front, one at the side and one on top? If the two houses are quite small and they both want to get in the same one it could be an issue possibly?
I think it was Tammy the Robo breeder who mentioned sometimes having 3 things for a pair can help - more options
