'MURDER, SHE WROTE'
At some point in the 18th Century, an architect, whose name is lost to History, built a mansion on a large estate in Jamaica. It was large and sprawling with beautifully detailed hardwoods inside and it came complete with a hidden passage that ran through the house.
While it was being built a Gallifreyan Time Lord visited the island and so loved the architect's work that he wanted the same thing built for himself on a small island he controlled in the Pacific Ocean. In every detail - at least with regards to its exterior - that second mansion was the twin to the original on the other side of the world in Jamaica.
And that Time Lord would be known as "Roarke", which was an alias meaning famous ruler on Earth, the planet he favored, (but among a people with whom he otherwise had no real connection.)
So that is why we saw two such identical mansions, to be found on opposite sides of Earth Prime-Time. As you can see, the only real difference between the two locations is in the landscaping, each with a different style of fountain.....