Voice remotes control the Roku via WiFi. They can only be paired to and operate a single Roku.
Non-voice remotes control via infrared (IR) control signals that work with any compatible Roku, so they don't need to be paired, in fact they have no provisions for pairing. Note that Roku TVs and separate Roku devices use different sets of IR control codes and so are not interchangeable.
Roku Community Streaming Expert
I am not a Roku employee, only a user like you. Please, no support questions via private message -- post them publicly to the Community where others may benefit as well.
If this post solves your problem please help others find this answer by clicking "Accept as Solution.".
Ultra 4800 | Streaming Stick 4K+ 3821 | TCL Roku TV 43S245/C107X