We hadn’t thought of it before, but yes, according to Chet Faliszek, of Valve, in an interview with VideoGamer, Portal 2 will have two separate credit sequences, one for singleplayer, and another for coop.
He also mentioned this:
“Both sets of credits [will feature something special], because we’ve got two credits, so we had to do something twice as amazing.”
Of course, VideoGamer fired away with a good question: can he tell us anything about these surprises in the credits?
“Noooooo, come on! The cool thing is that we’ll make sure that the game doesn’t get too difficult – it’s more complex – it’s never so difficult that you can’t solve it. You’ll get to the endings. We’d hate to think that people would only watch the endings on YouTube.”
That’s great to hear. The Portal 2 hype train just keeps rolling and rolling.