Dave, Yes the backs are black (I assume dip primed, hard to tell, I do not see any drips). I looked closely at the edge paint coverage. It appears the paint was applied from the top only. All edges facing up have the color, all edges facing down are still black. The sides fade from better coverage on the upper portion fading and showing more black towards the bottom. This is consistent on both sides. The sections that were clamped in the fixture do not have any body color on the edges.
Which means the paint fixture must have clamped the inside (screw hole portions) with the covers in their intended mounted positions, then painted with a single swipe with gun angled down. IMO the fixture must be lower than arm height to get the paint coverage that I see. (I tried to get a pic)