Though I was just made aware of this, I am apparently some sort of doppelgänger expert or genius. How do I know this? Because under the "Evil Twin" entry over at Wikipedia, there is an extensive quote FROM ONE OF MY TV COLUMNS that explains the difference between an "evil twin" and a "doppelgänger" (and of course, there is no difference). Observe.

If you watch enough daytime soap operas, then you already know the horrifying truth: Everyone on earth has an evil twin (or doppelgänger, if you will) roaming around and acting like a jerk. These doppelgängers are the ones who sleep with your best friend's boyfriend, steal prescription medication out of your bathroom cabinet, and spread vicious (and only partially true) rumors about your sexual proclivities. You have a doppelgänger, your dog has a doppelgänger, and your mom has a doppelgänger. Everybody has a doppelgänger—except for me. As it turns out, I'm someone else's doppelgänger.[20]
—Wm. Steven Humphrey, in an article from Seattle-based The Stranger

And because I am now internationally renown for my expertise in this subject, feel free to ask me anything you'd like on the subject of doppelgängers or the act of doppelgängering. YOU'RE WELCOME.