[BUG] Neutral/friendly doppelgangers that deflected PC's missile don't become hostile.
I think this is a bug. When you encounter a non-hostile doppelganger, it will of course deflect your projectiles as dopples always do.
However, despite this clear declaration of intent to kill from you, they don't become hostile after this.
I think shooting a non-hostile doppelganger and having him/her deflect the missile should instantly make it hostile as well.