Indeed I am using the first aid module... I think that it must be the reason, I've had a couple of other strange bugs when using the first aid module.
Eventhandlers seem to be ran twice sometimes and the player/killer variables don't seem to get passed properly in the onplayerkilled script.
Might just scrap using the module... what is the general thought of the module? I quite like the idea that you can become incapacitated but it does become a complete pain in the arse sometimes.