Remote wall boxes that plug into wall outlets come with a clicker that comes in different frequencies, i.e. A, B, C, D. The clickers also states which channel clicker it is, so you won't mix up the combination.
Within a room you can have several boxes of the same frequencies to turn on a lot of lights using only one clicker. You can plug a power strip into the wall box for more connections too.
You can use a different frequency in an adjoining room.
Using different frequencies keeps you from getting two different rooms screwed up and out of sequence. If you should have this happen, just unplug the box and let it reset itself!
We have Christmas lights throughout the house and ten big and small trees plus white decorating lights, also some white lights on bushes outside. Turning on lights is rather simple now!
TIP: If you are no longer using the remote box and clickers, remove the battery from the clickers.