Apple TV remote controls multiple Apple TV

I have two Apple TVs in separate rooms. When I change Screens on one, the other also receives the signal (not IR)and changes its screen also.

That shouldn’t be possible as each Siri Remote is paired with one Apple TV box, and then automatically unpaired with all other Apple TV boxes. It is always a one-on-one connection.

Try these troubleshooting steps for any unexpected remote behavior: If your Siri Remote isn't working - Apple Support

When I change Screens on one …

Please elaborate. Do you mean just navigating around, or something else?

You should be able to go into remotes and Bluetooth and delete the second remote if that’s the problem.