I think that in large part, the honor system is in place. As I understand it (and I'll defer to others more knowledgeable), divisions of a plant and mericlones of a plant are considered to be vegetative growths of the original plant -- so if you have a cattleya that gets an AM, all divisions of that same plant should carry the same clonal name and also can have the AM attached to their name. That is also why when you buy a mericlone, it comes with a clonal name and awards if any (or at least it should). Other than genetic testing, there probably isn't a way to prove that two people got the same identical plant awarded with different clonal names.