Hi Teodor,
I think it was mentioned on the forum, some time ago.
To reproduce, set a camera with a physical camera attribute, change the prescale or/and the film translate.
Render it, all fine. RT it, should be still the same image, but if you change a parameter in the physical camera like the ISO for example, the image (in RT) will change and the camera prescale and/or film translate gets ignored, shifting the image.
Cheers,
Yannick