I don’t think that’s correct. You can have 1 nano sim and 1 esim, but not 2 of either simultaneously.

They are correct, and you are not. The 12 is as you say. With 13, you can have either 1 nano and 1 esim or two esim simultaneously. You can also have other esim plans stored and not in use.

Also, you can have 9 (or more) inactive eSIMs installed and one active eSIM and switch between them at will.