ok, so I’ve hade a better look at it. it seems each eye is indeed showing a different image as when I close one eye, the double image I’m seeing disappears. the images do not seem to be working together to create a 3d image
when I say the straight objects are curved, that’s not accurate. the example I was looking at were some reeds. when they were to the left of the screen, they leant inwards e.g. /////. when they are in the centre of the screen they are straight up ||||, then when on the right, they again lean inwards \\\\.