Just checked this again and it's not quite right. In fact, it'll be the third time this has happened:
1995/96 (Swansea and Wrexham were in Division 2, Cardiff were in Division 3)
2000/01 (Swansea and Wrexham were in Division 2, Cardiff were in Division 3)
2025/26 (Swansea and Wrexham will be in the Championship, Cardiff will be in League One)