Blacktails here still have them, I am not sure about our Mulies.
Depends a lot on where in California, in terms as to whether your various mule deer sub-species still carry antlers this month.
But back to the original topic concerning the pair of whitetail sheds;
Both antlers appear to have come from similar age-class deer. Could be they came from the same buck, because they are extraordinarily similar. But, polarized genetic diversity isn't that common in your region of the country and it could very well be that the antlers are from two different animals. I'd need to inspect them up close to know more, but it could be they're from two different animals at same age or one buck who feels comfortable within that small diameter habitat range.