With my name (and yes, they only use first names there too), I suppose if I wait long enough, there will be someone to come in with my name. Maybe not be spelled the same, but I'm sure my name is called at least once a day whether i'm there or not.
My point is, the boy's name is probably not as unique as dad thinks it is, and at the boy's age, he should know (especially if he's at the docs often) when he's being seen or not. And if he's not able to tell whether or not he's being spoken to, then he shouldn't be left unattended. I'd like to think that my kid is just that extraordinary, but he's probably not as much as I think he is, but even he knows when he's at his doctor as opposed to someone elses.