n., a person who regularly inserts unsolicited advice, anecdotes and opinions into a conversation, especially ones in which they are not directly involved.
A two-center often interrupts a conversation's flow to pepper the dialogue with tangentially related stories and phrases like "the thing about that ...," "the truth of the matter ...," and "well, actually ..."
Person A: What's the easiest way to get to the Clarendon Metro from here?
Person B: Take a left at the intersection and it'll be four blocks on your left.
Person A: Oh, okay. Great. That's what I'll do. Thanks for your help.
Person C, The Two-Center: Well, actually you could take a bus to Glebe Road, walk to Ballston Mall and then take a cab to the metro. It would take you a few minutes less
Person A: Ummm, OK. Thanks man.