Yes, it is strange. But we have seem holes on other smurfs, like cleaner, groom etc. But as you say they look slightly different.
Otherwise the smurf is just as the first emblem-angry. Both have the peyo-marking on the arm on the same place. Injectionplace is the same, black paint is the same, material is the same. Eyes are a bit more orange, but that could just be mine?? And as the other early smurfs without emblem it don´t have any cavitynumber.
The front of the BP Shield magazine from april 1970, Lia showed in another thread, probably shows the smurfs BP used for the promotion. But we know Schleich made the Spy and Gold also. And since the spy mold was made 1966, it probably also was used in this promotion. Maybe they used some smurfs a shorter while compared to others??
I think it is a bit odd that the papa with peyomarking is way more common compared to the other smurfs without emblem. Maybe Schleich did not add the emblem to that mold until late 1971, because the first emblemvariation is pretty rare??
Hard to know exactly.