I've managed to calibrate my iPhone to work well in my google cardboard headset by using the "Cardboard" app from Google. https://vr.google.com/cardboard/viewerprofilegenerator/ I can run the demo apps without any problems, I don't see double etc. However, the calibration doesn't apply to my own VR app. Why are the calibration settings not connected to it? I don't think I've set up the VR environment in Unity wrong...
Transfer viewer profile to own iOS VR app
Transfer viewer profile to own iOS VR app