A Toshiba Fire TV, the Fire TV stick and a Fire 4K TV box plus an Echo and Echo dot. I have yet to have an issue.

But if I did I'd go to the unit that is picking up the wrong remote and tell it to forget remotes. Here's an Amazon article on that.

I think it's in the "elect Settings > Controllers and Bluetooth Devices" area so unpair that remote.
https://www.amazon.com/gp/help/customer/display.html/ref=aw?ie=UTF8&nodeId=201740060