Is it possible to use multiple of these withour interfering with each other?

discussed with product support and they refuse to say how many frequencies they use. units are not labeled. from experience more than 6 frequencies

I have two of these products and the remotes that came with each only worked on the switch receiver that came in the same package, they are unit specific.

Thank you for your question. There are 5 different frequencies of the receivers and remotes. They are coded with a small sticker on each product A through E. If you get 2 of the same frequency, one remote will work both receivers. The frequencies are different so one house does not turn on and off the neighbors lights. I hope that helps.