Dan Pastorini '74 Topps error card

I have had this card for over ten years and have always wondered how it got out of the factory. On the front it looks ordinary, a little miscut, not uncommon for that set. On the back it gets weird. When you turn it over, not only is it upside down, but it's not even Dan Pastorini's stats on the back, it's actually parts of four cards, Willie Young, a checklist, and the edge's of two other cards. Knowing that cards come on sheets ( I have a few uncut sheets) this has to mean the entire sheet is messed up. Seems pretty rare that a mistake like this got out.