Birds used in ceremonies are white, and are Racing Homers, yes. They return home and can be used over and over again.
Most Racing Homers are NOT white. Most rabid racing guys do not fly any white birds, and shy away from those with a lot of white on them, due to the fact that they are easier prey for Hawks, due to their sticking out in a flock, and to the fact that white flight and tail feathers become frayed much more than the normal dark colored flights and tails. AND, when these well trained athletes are in a race, they need every advantage they can get.