It's not that uncommon to come across various bugs on the PTR. This one's particularly interesting and allows players to equip a whole "set" of legendaries at once on the 9.2 PTR.

Content creator MrGM noticed a bug with Unity, the new Legendary Power coming in Eternity's End on the PTR. The bug allowed him to equip a legendary item in every single gear slot. Unfortunately, the effects did not stack.

Player wearing a full "set of legendaries" on the 9.2 PTR.

Below's a video showcasing the bug. 

Source: News Latest Topics https://www.icy-veins.com/forums/topic/63985-player-equips-legendaries-in-all-gear-slots-on-the-92-ptr/