so, it looks like if a new user registers during checkout, they get the order in My Account, and then if they come back and place another order, then that also show up in My Account.
for pre-registered users, as mentioned earlier, they don't get anything in My Account, but also noticed that when they come back to order a second time, their primary phone number is showing in the secondary phone number field.
what is different about the way the cart registers a user and the way native dnn registers a user?