It must have been shared with at least one other person as it explicitly states that there is only a single copy in existence. For us to be reading it means either the recipient or the person they shared it with subsequently shared it with others.
The first time I read it, I also had that interpretation. On subsequent reading, it does seem like copy meant a copy that is not the original. Not so much, "the only copy in existence".
Suffice it to say, I was sufficiently confused as well.
