First of your video is a 2 sec duration which can't even tell viewer what he/she was seeing. Too short length imo. In that time of recording someone could also be bugged so no one can decide what was it. Record at least 20 seconds for things to make sense and get clear
Secondly, your another video shows the bug and this is why I came here to explain my theory how this could have happened.
So basically when duel is about to start and map changes, system reads us under spawn protection (actually we were not supposed to be under SP as we never reclassed as civil back again). No one can either damage me or someone nor I or someone can damage someone else under that SP. So that happened in just fraction of seconds while dueling.
More bug related video is as follow: