I suspect that drawing was a goof. If they were thinking of using two roll pins to eliminate rocking, it would have made more sense to install them at right angles to each other, while the drawing shows them in parallel.
I agree that right angles would be superior but economical engineering would prefer a drilling jig that only had to shift along one axis. I don't think the drawing was a goof. Also, parallel dual pinning was already accepted sound engineering practice -- there are examples with transmission shafts.
