I can see a scenario where this may have come about:
1) Saxophone player decides to get into the high profit line of clarinet playing, on his own, without any teacher/mentor intervention
2) Erstwhile saxophone player discovers, to his chagrin, that his classic saxophonic embouchure does not function well on the clarinet
3) Player decides to take matters into his own hands, thinking that the problem must lay in the choice of the wrong mouthpiece, a common enough saxophone player belief for anything having to do with the tone
4) Player decides that, if XYZ brand 'piece works well on his sax, it would probably work as well on a clarinet if only it could be made to fit
5) Player has access to a friend with an electric motor and a big enough chuck
6) Friend, rolling his eyes the while, turns down the shank, cuts the groove for the cork, and hands it over.
7) Player tries his new mouthpiece for about thirty seconds, then decides to recover some of the initial investment by selling it on the secondary market