Double pendulum clocks are uncommon due to their complexity. 

However, when arranged in anti-phase they can be made more stable by transmitting energy back and forth between the duo. Essentially the pendulums are communicating with one another to cancel errors. 

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About a dozen double pendulum clocks have been made over the history of Horology. My interpretation would be driven by a modified gravity escapement acting on both pendulums with the conversation taking place 

via a flexible coupling. 

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Interior lighting above the movement. Black piano case.