They may have wanted to install the older version until their stock ran out, then used the new design for the rest of the 17's. That means one thing then... they are likely plug and play and retrofit-able, and i'll likely be contacting the dealer to see how much it is to swap out for the new design. I am not a fan of the 3 screens to be honest.
This is very interesting, I will get on it as well...I do know that the McLaren Internal Portal system is down for another 10 days or so as they transition to a new OS...not sure what is available.
We have a 2016 570S with the three screens and I think the new single one looks better. Also the 2017 has that little raised area for the locking sensor which is a nice improvement over mine as finding the touch sensor in ours always feels like trial and error. Well done on minor improvements from year to year McLaren! I was particularly vocal about that lock sensor so I'm glad to see they paid some attention to it.