My 23 month DD started gathering words at about 17 months and (I think) is doing well - she talks a lot! Mostly pointing and naming words, but putting together 2-3 words sometimes and also uses words functionally to get what she wants etc.
But she can also repeat words. Mostly when she's pointing and wants our attention (when we give it, she stops) and sometimes when she says a word we don't understand... I mean repeating. She can say it over and over.
Also, she has a way of saying people's names (or certain people's names) out of context, like she's been thinking of them. Suddenly say grandma or Marky (her friend) or a case worker at the nursery (she's just started, so quite excited).
Is all this normal stuff at this age? Have no idea!
I think it is. My dd only started talking at c30mths and you can't shut her up now.sometimes it's complete gobbledygook other times its as clear as a bell. I think their little minds at working so hard and so quickly it just pours out their mouths before they can process it properly. Your ds probably thinks he's talking absolute sense. IMO I wouldn't worry.
My 2.2yo DS also used to repeat and repeat until he got a response - I found if I just went "oh, yes, you saw a car huh?" he would kind of move on to the next thing. Even now he will sometimes get fixated and just repeat a question or something until he gets a response.
And he will often bring up things that happened days ago and I have to rack my brains to think of what he is remembering - I think their memories are actually quite good at this stage. We went back to a park recently that he hadn't been to in about 6 months and he was talking about "buds on trees" and we had no idea what he was on about, and then remembered on the way home that his Granny had been showing him (surprise surprise) buds on trees at the park.
So, yes, that sudden commenting on a name is probably just her thinking of them - they don't really have an inner monologue yet so everything is just blurted out I think.