When I was in high school most of the teachers were Nuns. Most of them took different names when they entered the convent. I remember Sister Reginald, Sister Mary Michael, and Sister Helen Patricia. Do Nuns no longer take new names when the go into the convent?
It depends on the order. I believe the good orders do take a new name.
And there are even traditions within orders. Charities BVM took their parents’ names—Sr. Mary Johnellen, Sr. Mary Joann, Sr. Mary Danetta. And Mercies (RSM) took single names—Marise, Florita, Arnold, Charles, etc. I think the loss of the habit was accompanied by loss of the new name.