Not a fix. Just a potential way to maybe ease things off:
When this happens, have you tried to hit your <Backspace> key?
For reasons that I could never figure out, I have some key repeat problems once in a while, with certain keys, in my Arch Linux installation. I eventually gave up on looking for a fix for it and accepted to live with it. But I can stop mine by pressing <Backspace>. So it isn't that bad. Just a moderate annoyance. This is obviously no satisfying solution and I hope you find the fix for yours. But in the event it would save you from having to kill RStudio each time, I thought that I would throw it out there.