Once the mind has been transferred to an artificial substrate like a computer, it would be relatively trivial to make two, three, or dozens of simultaneously active copies of a person. Maybe your spouse will duplicate too, and then the lot of you can fight over the house.
Similar complications arise in the legal arena.
People would still be allowed to make backup copies of their brain information, to be activated in case of an accident. But to purposely duplicate yourself would be prohibited. This is a difficult issue which involves personal liberty and social stability. More discussion would be welcome.