I was told recently, by someone who should know, that all Model S cars were built with dual chargers fitted, but only one was activated. If the other was paid for - then this is activated by software and can be done remotely.
This was rumoured to be the case for UK cars specifically, and probably only for the first few cars delivered (which also suffered from the 26A vs 32A limitation that all european cars also had until recently fixed).
Most home charging in the UK is 32A single phase. European-spec cars previously were only specified at 16A per phase (single charger) and 32A per phase (dual charger), temporarily reduced to 13A/26A respectively due to a design deficiency discovered soon after (mainland) european deliveries started.
So Tesla were in a bit of a bind on the run up to UK production - anyone who had ordered only single charger was going to get an unpleasant surprise of charging at only 13A on a home 32A charge point installed under the government scheme.
Tesla went through several iterations of how to fix this: a few people had special 'tweaked' chargepoints installed by Chargemaster (believed to feed the same phase to multiple phase pins on the connector) but these were then replaced by ordinary ones: maybe because of incompatibility with non-Tesla EVs, or maybe because it didn't fix the problem given that there are lots of public single phase charge points out there too.
Then it is believed that the first few cars had the second charger fitted whether ordered or not: some people found they could charge at 22kW on a public 3-phase point even though they had ordered only single charger, but then found that this was reduced by a subsequent software update back to the standard 11kW.
Finally, it is believed that a redesign - possibly part of the fix for the 13A/26A problem, possibly separate - meant that single charger cars could charge from 32A single phase and so the spurious second chargers are no longer being fitted. However, this hasn't been totally confirmed - we need someone with a recent single charger car to lift the rear seat and see what is in there.
Will also be interesting to see any single-charger cars visiting from the continent that have had the fix applied - can they get 32A out of the various 7kW public charge points (Source East etc.)?