Additional fractal avenger spawn at the end of vapor form was removed in a patch in 2016, but now it's back.
September 20, 2016
The elementalist downed-state skill Vapor Form will no longer spawn an additional fractal avenger.
I got stomped few times because 2nd one spawned right on top of me after running away from first one.
Also a lot of the time , vapor form goes on full cooldown, without it's effect being triggered. Not sure what causes this. I think if you press it too fast after dying it can cause bug and also it felt like it has to do something with quickness/alacracity.