I am not sure if round and square edges are made from different molds or not. I will ask, the first time I get a chance.

I do know that you can empty a box of new Paulson chips on a BJ table and the table will be covered with dust. Looks like brick dust. Edges rounded or square could have something to do with who removes or how they are removed from the molds.

Could be the Mexicians use machetes to remove some of them.