Original: IAU Circular 3608 describing the discovery of S/1981 N 1 The moon was recovered and confirmed to be the only object in its orbit during the Voyager 2 flyby in 1989 [on page 1435] after which it received the additional designation S/1989 N 2 on August 2, 1989.
Simplified: The moon was refound and confirmed to be the only object in its orbit during the Voyager 2 flyby in 1989 after which it received another designation S/1989 N 2 on August 2, 1989.