why would you need two of those for said strategy?
Actually I think he means 3 necropoli as big zig in itself refers to a 2nd necropolis. The advantage of big zig is that you save lumber (necropolis provides the same food as a ziggurat but costs more gold and no lumber) and can tech faster (as you can still make acos or even expo while teching).
Let the Dragon ride again on the winds of time.