Yep, looks like the upper piston cycles twice in the four strokes of the main piston. The top piston comes down on the compression stroke, possibly allowing for more fuel/air, and higher compression.
Seems to me like that might work, but might need higher octane fuel to avoid detonation. Also having another piston makes the engine bigger, and heavier. Also internal losses from more parts having to be moved... I would be interesting to see how much more efficient it could be.