I think there's no marker. Both instances of you feel like each of them is you, if the copying was sufficiently faithful.
Concepts of the original and the copy are external to them. When you imagine the situation you take a place of external observer who has the information about who is the original and who is the copy.
ETA: It's something like imaging your death. You cannot truthfully imagine it first person, and (imperceptibly) slip into third person view.
Concepts of the original and the copy are external to them. When you imagine the situation you take a place of external observer who has the information about who is the original and who is the copy.
ETA: It's something like imaging your death. You cannot truthfully imagine it first person, and (imperceptibly) slip into third person view.