I use 2 at the same with no problems at all. Just label them units 1 & 2 or A & B so you wont get them mixed up. They are great units. I never lose signal and my smoking area is at least 50 feet from my living room, plus theres 2 walls in the way. Goes through walls just fine. Plus theres a sexy voice that lets you know your meat is "almost done". I give the unit 2 thumbs up.