They graze in the same area and have the same genetic inheritance, and they could both be from the same Cow with a common Bull as their sire.
The evolution is now going away from dark color to white, a predictor that we do not have global warming now and are moving to a much colder climate era, where moose blend in with the snow and ice.
Interesting. It just seemed to me that even with common parents, the likelihood of two white ones would still be low (?)