I haven't had time to write any comments on the recent doppelganger events, but the doppelganger motif is one that has always fascinated me ... I believe Poe made use of it, though I don't remember specifically in which works, as did Dickens in many of his novels (e.g., there is an eerie scene in "Our Mutual Friend" in which the main character -- whose name escapes me -- literally views his double laid out on a slab in the morgue) ...
I'm kicking myself because I thought I caught something important on DS -- a few episodes before the revelation about Barnabas -- that raised a question about the whole upcoming doppelganger possibility -- but I was viewing late at night, practically falling asleep, and didn't write it down and have since forgotten what this could have been ...
I am curious about the connection DS made between mirror magic and doppelgangers -- as Angelique's mode of creating Barnabas's. It certainly makes sense, but I wonder if this was original to DS, or if the idea is common or appears elsewhere ... does anyone know?
I discovered some old notes of mine that refer to an early medieval treatise, "De Configurationibus qualitatum," by Nicole Oreseme (1320 - 1382) that is supposed to discuss mirror magic, but I haven't been able to look into this further.