All transmitter operate on the same frequency. The regulations require that the duty cycle be very low, depending on the band from 0.1 to 10%.

So, as long as only one trasnmitter is ON, there is no problem. That's why you can unlock your car, when all the cars and remote door controlers are on the same channel.

Regarding the SMD or DIP case, I suppose you have to call Bruce and ask him.

Ioannis