Death's Dance Bug not giving multi-kill credit? (Not Sure)

So I was playing after being inspired by Stixxay #TheYoungHopeForNA and during a team fight when I killed two members of the team in quick succession I realised that I wasn't given a "double kill" in game. I saved the game by plays.tv as you can see where after I kill the (killing through the DoT on his Death's Dance seconds before" it just says shut down. I was wondering if this was a bug. Another possibility that popped into my head was that the time of death was counted from the time the auto that would've killed him (without death's dance) is counted and not the time it ticks down. I'm not 100% sure.

Edit: Looking at the video again, even if the second possibility was a thing, timer was still live for a double kill. So yeah I think it's a Death's Dance bug.