Who is Marcia and Vanessa from Sybil and what is their importance?

Vanessa Gail Dorsett and Marcia share Sybil's body simultaneously. They are not sisters, and they did not emerge at the same time, but they have developed a close friendship. Vanessa is described as lively and outspoken, much to Marcia's chagrin. She dreams of traveling, and she loves to both visit museums and listen to classical music.