Check out the players here: https://www.roku.com/products/players
If it states "Simple remote", it's an IR remote. If it states "Voice remote", then it's an RF remote. I think only the basic Express (not the 4k+) comes with an IR remote these days. You could get any two that use an RF remote or one Express and any of the others. The sticks only use RF remotes. The others will respond to IR or RF, so if you got one Express and one that isn't a stick you'd have to cover the IR sensor on the one that isn't the Express.
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