PICTURE AT LEFT
These two stallions are sparing with each other. these stallions enjoyed doing this often. It is a good possibility that one stallion on the right is the offspring of the one on the left. The dominant stallion is on the left. The submissive stallion is on the right.
Here is another photo of a couple of stallions. It looks fierce but there is seldom any contact. I have seen many threats made by horses. I never witnessed what I thought was a true fight.