Android duplicate SurfaceView

Question

I want to create an android app with a surfaceview that fills the left part of the screen and with another second surfaceview that fills the right part of the screen.

In both surfaceviews should be a preview of the camera. So that there are two exactly similar camera pictures side by side.

I tried it like this (i will remove the button and onclick part etc when i solved my surfaceview problem):

 getWindow().setFormat(PixelFormat.UNKNOWN);
   surfaceView = (SurfaceView)findViewById(R.id.surfaceview);
   surfaceHolder = surfaceView.getHolder();
   surfaceHolder.addCallback(this);
   surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

   surfaceView2 = (SurfaceView)findViewById(R.id.SurfaceView02);
   surfaceHolder2 = surfaceView2.getHolder();
   surfaceHolder2.addCallback(this);
   surfaceHolder2.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);

  buttonStartCameraPreview.setOnClickListener(new Button.OnClickListener(){

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
if(!previewing){

 camera = Camera.open();

 if (camera != null){

   try {

       camera.setPreviewDisplay(surfaceHolder);
       camera.setPreviewDisplay(surfaceHolder2);

} catch (IOException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}

   camera.startPreview();
   previewing = true;


 }
} 
}});

But obviously it just displays the preview in the "last" surfaceHolder (here: surfaceHolder2). I hope you can help me :)