Hi Mike! The diffuser gasket has metal (copper?) inserts in the mounting bolt holes. When tightening the mounting nuts to the studs these inserts must "crush" slightly to allow the insulating/sealing surfaces of the gasket to fully contact the carb base and int manifold. Some guys will pre-crush the inserts slightly to avoid putting excessive torque on the carb throttle ears when tightening.
Rick, If the diffuser/gasket is NOS and came with his NOS carb, it will not have the copper inserts. The old original gaskets were stapled together and there were no inserts in the bolt holes. Another case of "If you can make a replacement part, why can't you make it correct?" BW
Bruce you are correct in that the old design did not incorporate copper eyes in the material. Jeepsaffer did not elaborate regarding the gasket that may or may not have been in the box. As far as the ideas of the engineers go, I do not presume to know why the eyes were added except to assume that the eyes created a better seal around the studs.