You can only have one Maya scene open at a time... Unless you open each scene as a new Maya window" application running" .. I,ve never had more than 2 maya programs running at the same time.... Only when I might need to show 2 different files to an Art Director...I ' m sure you can have more open depending on your computer and the size of the scene.
Unless you are talking about "Scenes" as in shots in a movie... Like switching cameras?
