If this is a fourree (that would explain weight and some details on reverse), I would suspect the obverse test cut was one of the "fake test cuts" placed there by the forgers before it was plated. (Of course, it is possible for a test cut to fail to break the plating.) I know the phenomenon of "fake test cuts" is well documented for Athens tetradrachms:

From CNG
[acs Link] But I've never seen it on an Alexander/Philip III tetradrachm. That would be a really cool discovery, in my opinion.
The question for me: did the forgers cut the cores manually, then plate them, or was the cut actually part of the original die (which would be technically quite impressive!). I'm having trouble finding them with keyword searches, but i had the impression that I'd seen a couple of the owls that looked similar enough to be from the same dies, but I could be imagining that part....