I have 3 Roku Smart TV’s 2 are Hisence and 1 is Phillips, every single one of those remotes are universal, they work for each other’s TV, my Phillips works on the Hisence TV, and the other way around, and the Hisence remote works on the other Hisence TV? Why is it like this, couldnt this be a security risk? For example if I knew someone else who had a Roku Smart TV, my Roku remote would work on their TV as well.
But you would need to be in the same room as the tv, so what's the difference in you using your own remote you brought with you or one sitting on the table? IR remotes don't go through walls. Roku TVs use two different IR code sets, Hisense and Sharp have their own code set, problem as you found out Hisense responds to both code sets. You Philips remote will control the Hisense, but Hisense remote won't control the Philips Roku tv.
You will have to abandon the oem IR remote from all three TV's and upgrade to wifi voice remotes, which only pairs to one Roku tv at a time.
Edmund Roku Community Streaming Expert
Help others find this answer and click "Accept as Solution." If you appreciate my answer, maybe give me a Kudo.