Looks like a bug to me. Here's the steps:
I have a RAW file and a virtual copy of the RAW file that is cropped.
I export both to create jpegs and add them to the current catalog.
When I view both jpegs in Develop mode with cropping tool on (keyboard command "R") the cropped jpeg looks fine but the jpeg of the uncropped RAW file looks squeezed horizontally. If I change to library mode (keyboard "E") the jpeg looks fine. If I change the cropping in the develop mode to 1x1 and then back to "original" it displays correctly.
Anyone else seen this?