Look at this:
A
A: right, curved edge, thick, with knuckle indentions. just as we know it
B: left, straight edge, thinner, less pronounced knuckle identions if at all
This makes believe that there was a third version, a "straight edge" version and ll were constantly mixed up
BUT: Can somebody tell if this image is flipped? If so, there's only a right "straight "edge
Back to work!