Why not? The US, for example, recognizes a copyright in architecture. https://en.wikipedia.org/wiki/Copyright_in_architecture_in_t...

Dépends. If the 2nd house location requires review by an architect because of ground issues or regulation. If contractual provisions require an architect fee. If small adjustments that may have structural impacts are needed. You won’t pay the same amount, but still something.

You're quibbling. That's really not at all the same as paying an architect to design an all-new building.

Not quibbling. That’s not the same order of magnitude but it’s real life. It happens and can be a significant part of revenue for the architect.