Sorry if this is a silly question but if the R key and one of the controller buttons do the same thing, would that be allowed?
Or would I have to unmap Respawn from the R key as well so I don't technically break the "Rebinding one key to multiple inputs or multiple keys to one input is banned" rule?

i'm curious about this as well

Sorry, I'm not sure why this didn't get answered right away.
Assuming you're not playing with keyboard and controller at the same time, it's all fine. I don't think it's been discussed before what rules apply when using e.g. controller and keyboard simultaneously, though.