From the README:
The TwinView feature is only supported on NVIDIA GPUs that support
dual-display functionality, such as the GeForce2 MX, GeForce2 Go,
Quadro2 MXR, Quadro2 Go, and any of the GeForce4 or Quadro4 GPUs.
Please consult with your video card vendor to confirm that TwinView is
supported on your card.