Two Rattlesnakes Dancing, Fighting, or Mating?

Occurred on September 4, 2017 / Ladera Ranch, California, USA

Info from Licensor: "I was returning home from a mountain bike ride in the hills above our community when I ran into two Southern Pacific Rattlesnakes. I was close to full speed on a downhill portion of the trail and nearly took a spill when I realized there was something blocking the path. Turns out the snakes were either mating or performing some sort of aggressive dance to impress a nearby female. It's a popular trail for mountain bikers, hikers and dog walkers, but it is important to note that I was in their environment. I am not a big fan of snakes, but seeing something this rare in the wild had me sitting and watching for twenty minutes."