Sprocket Wheel 57519 Alignment of Centre Pin Holes incorrect

[Orion Pobursky]

Why is that, I always thought 'b' ones are only intended for mold differences not mistake corrections. Otherwise the library would hold more corrections then real parts.

Most corrections don't warrant a variant. However, in this case since the orientation of function elements of the part will change, this would "break" the part for those model that already use it and so needs a variant.