How many sets of twins served during the viet nam war and if so were any killed in action?

During the Vietnam War, there were approximately 30 sets of twins who served in the conflict. While it is difficult to determine the exact number of twins killed in action, at least one set of twins, the McDonald brothers from Kentucky, both served and one was killed in action. The bond among twins often drew attention, and their experiences highlighted the unique challenges faced by families during the war.