I have seen quite a few of these in this condition, where the center area is unplated. In my experience, ones appearing like this are almost always altered. It looks a little too uniform on both sides. I have also never seen any that mimic this type of pattern slabbed, only loose. Below is a legit one from my collection.
I can see how on @JCro57 s example the lines are well defined but on the pmd example the gray area simply fades off
