This scenario occurs if the student withdrew from the school and then decided to come back to the school. For example, if the student is in the Past Student role due to withdrawing from the school and is now coming back to the school, they will have enrollment rows for a previous school year as well as an enrollment row for the current school year. So in this instance the student previously attended the school and also appears in the Students - Returning vs New report because the are newly enrolled in the school in the current school year.