hi,
perhaps heuer had ordered a smal batch of prototype/test dials from perhaps different dial makers, possible is a preprint too. for producing the adverts for the marketing, they used the ones they got first, but deside later to use another one.
for some circumstances all the dials were monted while production....but this is speculation.
one point is the smal amount of dials and the specialities of cliche/printing to be quick.
cheers mich