(There are only 2 known)... though only mine shows both sides in ChipGuide.

Though, the history might have had an influence... five years after completion (1929) of being built by a famous American (family) who did chips in a hig way, here in the US.

Nobody that I know of in the past 29 years knows why a (?)... though, it might be very obvious why.

It was found in a Paris shop and someone in town (I don't know who) suggested it be sent to me.

Anyone is welcome to connect the dots and give it a shot as to why a (?).