odd crossover ports in early dual plane holley?

The intake has provisions to install an EGR valve on it.
You had to drill open the spots on the manifold for the flow & to link up with the port in the plenum.
That's the reason for the hole in the plenum, like any OEM EGR manifold.
It is also a single plane intake with what Holley called a balance tube on the back left & right runners.