[Graeme Dice]

Originally posted by raynor:
Ahhh... the time honored defense of the lazy programmer. It's not a bug. It's a feature!

There is no inherent reason to restrict spaceports to one per planet, and to do so would cause vast problems for those modders who might want to create a facility that has multiple abilities including spaceports. You left the queue on repeat build, and it functioned exactly as it was supposed to. It built another of the top items.