It sounds like what you are thinking of is part of the doppelganger portion of this event. The changelings impersonate smaller creatures such as gelflings, goblins, animals, or even plants, while the doppelgangers impersonate the Dreamers. They do attack with the intent to kill if provoked as well.

So, yes, Roche will be able to face off against himself, but it will be against his doppelganger, not a changeling.