When I first saw these on eBay the other night, I tried zooming in as close as possible to see if the break was there or not. Then I went to a couple of older BG plaques that I have in storage and it was very close to your examples. I then went through some 1969 production from BG, and the continuation of the border at the corners was a little thicker or wider... and I had also asked here if anyone had any early Abbiati plaquesm

The red one I show here is 1969 manufacture.. and I have earlier which is even thinner and yet older which is thicker but, one thing for sure; the Abbiati manufacture is clearly different than BG -- in more than one way, too. Spregg pointed this out years ago.