Well, it would have to be a person with access to the
MDE account associated with the reservation, or they would not have access to the reservation to do online check in. They also can tell (if you use magicbands) whose MB is used each time the door is opened. I do not know if they can match the phone number to the number on your MDE account if you choose to use your phone to open the door, but it would not surprise me if they can.
I am sure it’s not 100% error proof, but I have been doing it multiple times per year every year since it’s been offered and so far (knocking on wood) I haven’t had any problems.