Conversation Déjà vu

When you're talking to someone about a topic you've already covered (but don't remember covering) and you find yourself being able to complete each other's thoughts.

friend: You would not believe what happened to me!
guy: What?
Friend: So I was running this morning when all of a sudden the craziest thing happened!
guy: Did you get attacked by a dog??
friend: YEAH! Whoa, did we already talk about this?

guy: Oh yeah we did, just had a moment of conversation déjà vu