Did the garlic wrappers have purple stripes? Did it flower and have bulbils in the top? They say that Caulk White can have quite large cloves, but the other features should show a clear difference.
Caulk is a hardneck, so should have flowered and produced bulbils. Elephant garlic also flowers but does not produce bulbils in its flower head. And elephant garlic wrappers do not have purple stripes, they are white. Elephant garlic when dug up, usually has small bulblets in a hard brown wrapper hanging off the bulb, hardneck garlic does not have this at all. Did you see bulblets when you dug the cloves? You could not have missed them, they are so obvious.
If you go by clove size alone, then it is quite possible that you have relatively few cloves in a bulb of a hardneck variety, but that these are bigger than the average softneck garlic. Softneck garlics do not flower, but make more, smaller cloves. What are the other characteristics of the garlic?
I do not think that they have changed species, but that with good fertile soil, you got maximum size bulbs possible for this variety, whereas what they sent for seed bulbs was probably smaller.
https://www.thegarlicfarm.co.uk/products/caulk-wight%C2%AE-seed