It is okay for kittens to choke on milk and fight with their eyes closed. It is a normal phenomenon and generally will not be injured. However, it is best for the owner to watch from the side. If the fight is particularly fierce, separate the two kittens. Generally, kittens fighting for milk are because the mother cat's milk is insufficient, so the mother cat needs to be supplemented with nutrients. You can feed crucian carp to increase milk production, or you can make goat milk powder yourself and then pour it into a bottle to feed the kittens.