Panel 1: It would appear that the man I refer to as Doctor Shotgun is Doctor Don. That's because as they sign up for the TMJ workshop, John tells Don to sign in for him so that he can arrange a room for the night.
Panel 2: When he gets to the front desk, the clerk from last Saturday apologizes but the best she can do is a studio with a fold-out couch; this causes John to tell her that he'd registered weeks ago.
Panel 3: She then looks at the screen of her terminal and tells him that she's checked and he's simply not there. He looks at the screen and asks "I'm not?"
Panel 4: This is so he can tell her to find out who is standing there wearing his suit.
Summary: As someone who understands computers better than Lynn does, I find the excessive trust the woman puts in the machine to be something of a joke. While I can see that John only thinks that he booked a room or that he booked for the wrong date or that the data entry clerk cannot spell, I don't think that she can see the last two because she doesn't realize that machines are designed, built and operated by fallible human beings.