It depends on how you are looking at what you consider to be in unison. The men’s legs are equidistant apart, their bodies are about the same distance apart, legs are straight, arms are in similar positions, and each is striking with a heel and pushing off with a toe. If one of them was in a midstance with their knee flexed, then I would consider that not to be in unison. Here are the shots from that day. Which would you consider to be in unison? (Or how else would you describe why the photographer chose that particular shot?) Another example, if a crowd yells in unison, does that mean they all yelled at the same pitch and volume?