anivia's E seems to hit twice at times in one instance?

i was playing in PBE against a zed as anivia and noticed when i used E on him it dealt the double damage twice in one instance instead of regular damage in one instance, as he told me the damage from death recap, and there the damage had to have been quadrupled to have killed him, which meant E hitting twice

i don't have any evidence of it, but maybe a bug to look into?