Hi there,
My friend has a lo who has always liked a short am A time and since about 16/17 months has always napped from 11-1/1.30pm. I think this is fine if this works for you. I would be surprised if he 'needs' 2 naps at 19 months but again you know him best and if he really does then go with what works for you.
You need to look out for signs that he needs to just have one nap so EW's, playful or UT NWings and of course nap resistance.
Becky x