Clicking on the Multi-View button doubles the models

I want to click on the button to enable Multi-Views (Multi-Views-Two), and then click on the Multi-Views-One button to return to the original state.
Everything works ok, except by clicking on the button the models constantly double …, how do I correct this? Any idea?
My playground;

from a quick read, I would say that you need to first clear the scene.activeCameras before adding cameras in it