yes...2 or 3 times not sure b/c of how short the ko was.
also done it via air chokes.
i also once ko'ed myself via bowling ball.
anyways... the ko'es i was responsible for were short. i could watch them freeze up and fall over and then 3 seconds later start to move. it was funny but it wasnt nothing prolong like the movies or in professional fights.
also a sense of panic would kick in thinking i might have killed them.