We were in Beijing in 2013 visiting our son. We went to the China Rail museum on the outskirts of the city. A beautiful collection of engines and all very clean. I found 3 pictures that relate to two headlight steam engines. The first is Mikado that has one head light over the other. Neither looks to be a Mars light.
Here a couple of pictures of another Mikado that looks like it is related to Chairman Mao. Some of the placards were in English, some in Chinese. There wasn't anything I could read associated with this engine.
I think the head on picture shows pretty well that both the lights are the same and neither looks like a Mars light. These were the only two steam engines with dual light out of the dozens of steam engines in the museum. I would highly recommend a stop at this museum if you get a chance to visit Beijing.