In PvP it's perfectly "normal" to be still running around for up to a few seconds while already dead, because of lag.Not sure about the healing from death mechanic; I wouldn't rule out lag. But, I've also seen some pretty similar bugs when soloing group content. In vet Banished cells 1, I experienced pets giving a death cry and disappearing while I was still alive, pets attacking for a while after I was dead, (...)
... But in my "miraculous survival" attempt, I was locked into the 2nd execution only a couple of seconds after the first one finished. I haven't attempted timing this, but it did not feel like there would be enough time to burn Bandu before the 2nd execution finishes, even with some pretty impressive DPS.