Regression image sometimes to the left when comparing

[pstenstrm]

When you compare regression images to the baseline the baseline image is to the left and the regression to the right. But sometimes the regression will show up to the left with the baseline image to the right. This gets really confusing.

I can't show too much of the application we're running regressiontests on, but you can see that there's a 1px semitransparent border on the baseline image which is missing on the regression image:

Here the baseline and regression have switched places: