Oh, he’s a clever so-and-so that Steven Moffat. The fans want a multi-Doctor episode to mark the 50th anniversary, so he gives us not one but several. He’s been dripfeeding us echoes of Doctors One to Ten for weeks and when we sit down to watch the series finale, with – let’s be honest – half an eye on the November special, he gives us all Ten (blink and you miss Eight though) and in a way that makes sense.
He doesn’t, of course, tell us the Doctor’s name, because the power of it lies in its mystery. There is no name you can give him that can match his chosen name or the draw of the secret surrounding his other name.