They should be part of a random generator that allows variation in game. It helps allow multiple models to show for more diverse races (primarily the Imperial Guard since human appearance is diverse in nature). I've has games that have the gas mask troops, but other games I have seen none. It's just random.
ReconByFire
Coleten joined
I am currently a college student studying law to become a law enforcement officer. I enjoy many RTS games including Europa Universalis IV, Company of Heroes, and of course, the Dawn of War franchise. I also play the tabletop equivalent as the Imperial Guard. I am an easy person to get along with so long as those who wish to affiliate themselves with my friendship practice a manner of honor and loyalty to not only myself but to all. I enjoy practicing sportsmanship and professional attitudes in life, and I don't usually care what anyone has to think of me!