There are three cameras that work for Pass-through. One is responsible for rendering left-eye image only, another for rendering right-eye image only, and the third camera is for rendering all game objects except two image planes. You will need to accept the dual camera layer setting to ensure this module works well. There are some operations listed in ViveSR_DualCameraImageRenderer which demostrate how to use the data after capturing frames.
For more information, please see ViveSR_DualCameraImageRenderer, ViveSR_DualCameraImageCapture, ViveSR_DualCameraImagePlane, ViveSR_DualCameraRig.