You gotta be shitting me! NO two ARMDs are alike? What happens if one of them get fragged? They wouldnt be able to fix one with parts or armor plate that they had extra unless they had produced if for THAT particular vessel. If the stockpiles of spare parts goes up and the ship gets damaged its an expensive paper weight.
If the pics on the Macross II rpg book that covers the Macross are anything to go by, then the diffrences only seem cosmetic. Looking at ARMD-1 and 2 (the Macross's arms) the bridge is on opposite sides, but it's still the same bridge, and those things sticking out from the sides (manuvering thrusters? the main engines?) are shaped diffrently, 1's is taller, and 2's is wider, but I'm sure they share the gross majority of components.