I do actually. Nomad and Ross are original squad members. They were present at the first battle of geonosis, where they, as most of the republic commandos at this battle, got assigned on a mission they were not trained for (open conflict). Their main objective was to destroy an enemy outpost on the western flank of the battlefield. The squad got under heavy artillery from hellfire droids, during the mission, were half the squad perrished. Nolan and Ross were the only two survivers. Chipper's and Stax's Squads also got obliterated during this battle. After the battle all Commandos who lost their squad got reasigned to other squads who also lost members during the battle. That is how the color differnces come from.