No worries, I understood what you meant, but I wasn't very clear. The ends of the Krypto Fahgettaboudit U-lock shackle have inward-facing cutouts where the two pawls fit. If you only insert one end of the shackle in the lock, then that cutout is not aligned with the pawl and that pawl cannot be inserted into the shackle -- and thus the lock cannot be locked.

Further, the design makes it so if one end of the shackle is cut, the other end won't rotate.

Hope that makes sense.