I don't know how to attach a video, but I have a 42 second video of my character aggroed onto... well, herself, if the combat targeting information is to be believed. Both skeleton (necromancer skill) and her Companion were locked onto and firing at this "other" Neamhní Voidsinger, which appeared to be a spot on the wall.
I could only hit her (the Other, henceforth) with AOEs, as though she were an enemy inside the wall, so the targeting data didn't pop up. While I took no damage myself, neither did the Other - but if I was damaged in a nearby trap, it showed the Other as being damaged.
The Other also healed when I did, and clearly my game thought I was hitting something, as my character healed when using the Necromancer Scythe on the Other... and the Other healed as well.
All of this is covered in the video, but when I try to attach it it says "format is not allowed" - it is a screen cap MP4.