LIke I said earlier, WWVH and WWV can be on the same frequency because
they are perfectly sync'd up, at least for actual listeners. You don't
hear double ticks, and the only reason you know WWVH is there is because
they ID with a female voice, and and at a different time on the "wheel"
from WWV.
And of course, they aren't connected in any way, just well adjusted.