My contribution to the twins category are these two CD 152's. Picked by me off adjoining pins they have the most pronounced mold line I have ever seen on a glass insulator. In profile, a side view of the left insulator appears normal with the mold line highly visible. The right insulator is a frontal view and shows what appears as a distorted, almost squashed profile caused by the additional glass of the heavy mold lines being added into the profile.