LeeAnne is right ( of course
) .
Previously they also made moulds containing two or more of a model, in order to speed up production.
So already during manufacturing they could not find the location of a problem by looking at the newly made models.
I have some small, old Schleich with numers 1, 3 and even 7 !
Nowadays you see a sort of "clock-face", showing the year and month.
I suppose production methods have improved a lot, so maybe they don't need those old, complicated multi-model-moulds any more
PS : I looked up the word "mould/mold". It seems I learned the British way of spelling in school , while LeeAnn obviously spells the American way