Hi,
this happend before when i played a few years ago. While my Demon Hunter has transmogged Weapons, there spawns an additional Weapon on the back of the Character. Its always a green Illidari Crest. The upgraded green Vengeance Atrifact Weapon from Legion. When i transmog the Weapons back and forth its gone, but this costs Gold everytime. Hope there is a fix for this.
Thank you!