If a person needs a double lung transplant, are both lungs replaced during 1 or 2 separate surgeries?

One operation. During the surgery, they operate on one side at a time. The surgeons remove and replace both the right and left lung. It is therefore termed sequential bilateral lung transplantation.
Sequential single . The real name for a double lung transplant is sequential single lung; there is one surgery done where is lung is transplanted separately.