If both units accept the same code, there is really no way to seperate them. The only workaround I can think of is to cover the sensors of the one you don't wish to change channels. Probably not too helpful, but I don't have a solution for this scenario, unfortunately.
I have 2 Samson devices:
Each of them has a remote control, and both are in the same space.
However, the remotes are both on the same channel, so that when one is switched on/off, both devices are affected.
How can I change one of them?