When a student has a completed status in a curriculum, that certificate should always be available to the student as a record of their completion. The certificate should be available to students regardless if the enrollment is from a historical data migration or new enrollment/completion of a curriculum.
We have a huge amount of students - former students, that need historical data and certificates for their authorization status. Many of these students are required to submit "certificates of completion" in order to retain their "Professional Engineering" status.