Assuming these are Roku TVs (sets that have Roku functionality built into them), the remotes supplied by the manufacturers are typically infrared (IR) remotes. If you have the same TVs, as you said, then you have the same remotes and they would be completely interchangeable. Each remote will operate whatever TV its IR beam lands on. And depending on your room characteristics, sometimes the IR beam will bounce around and reach places you don't intend.
All Roku TVs can use the Roku Voice remotes. These control over WiFi, not IR, and must be paired to the Roku it is intended to control. Once paired it will only operate that one device.
Another possibility is to use the Roku Remote app on an iOS or Android mobile device. When using this app, you choose which of the available Rokus you wish to control.