Dan,
It's hard to tell from the photo, but it looks like a good size spur and appears like a males. The general build of the snake in the photo, and the length to weight ratio would also lead me to think male as well. I would suggest that you probe this green to confirm. They probe different than other snakes, and if not done correctly, all greens will probe out as females. As far as the breeding activity you observed, under certain conditions in the wild, male anacondas have shown occasional breeding activity toward other males. It's rare, but has happened.

Kelly