Help with the Asset Editor and Landmarks.artdef

[Magil]

So I've been having a lot of trouble with updating my mod and Landmarks.artdef, using the Asset Editor, and I think I've discovered the problem.

Look here:

For some reason, this BuildingSet is outputting the Temple element twice. I know this is an issue because it causes the Error district image to appear and it stops updating with the era change, but if I manually edit the artdef to remove the repeat entry it starts to work properly.

Can anyone more experienced tell me why the Asset Editor is doing this, and how I can make it stop? I don't have the temple entered twice into the BuildingSet on the right, as you can see.