Bob,
Yep, that's the way it works. There's a preamble (extender ID) in the code from the remote which notifies the extender whether or not the signal is for that unit. Now if you have an environment that has RF interferrence, you'll need to find the channel that minimizes the interferrence in all locations. At least that's the theory. I've noticed that the channel seems to make little difference. Other people have commented that they receive interferrence from 2.4 GHz phone systems. That frequency would be way outside what the extender uses. It leads me to believe that the extender's receiver is pretty wide open to anything in the RF spectrum. But that's just MHO.
Jim L