Rather than using a quad to hide the scene like I posted earlier, an easier solution is to set one eye to an empty scene:
Code:
import viz
import vizact
viz.go(viz.STEREO_HORZ)
viz.addChild('piazza.osgb')
#Show or hide scene 1 for the right eye
vizact.onkeydown('1',viz.MainWindow.setScene,1,eye=viz.RIGHT_EYE)
vizact.onkeydown('2',viz.MainWindow.setScene,2,eye=viz.RIGHT_EYE)