I think that dwarfs before Thanos killed them used a sophisticated system of mass production so they were doing many copies of a one detail at the same time. Eitri had no time(and hands) for fixing this mass production. So I think that the second mold is the same as for Thor's axe. We can even see that it is absolutely the same as
the first on the photo.
Also, Eitri didn't use that mold, what means he don't need this detail.
I don't change my mind but here is what directors answered to a related question here
As for Stormbreaker, Groot was alongside Rocket and Thor during
Stormbreaker's creation. While the blade for Stormbreaker was
finished, the mold fell over before the handle could be created, and
to save Thor Groot uses his limbs to form the handle and unite the
weapon, saving Thor in the process.