It happened a lot when model 3s first came out in the UK. In the period between ordering open (May 1st 2019) and the main set of deliveries* starting (August 2019) some people had 3 or 4 different VINs assigned (I had 2 myself, the second being the car I actually got).
I suspect it happens less these days due to a lower backlog and less complication around reservation date vs order date, but still possible and worth flagging that just because you've been assigned a VIN doesn't guarantee you'll get a car, or if you do that it will actually be that one (although in the vast majority of cases, it probably will).
* Yes, there were some token deliveries in June 2019, but the main thrust didn't start till August.