What I mean is this;
if you are running a 4-pin Ecu in a Dual-ballast circuit, the one ballast is in series with the coil, and the other "dead-heads" at the non-existent 5th pin.
If your Ignition craps out and you trace it to a faulty ballast, you just transfer your coil wiring to the other ballast, which, until now, it hasn't been doing anything. In other words, it has been your back-up/spare. It doesn't matter what the ohm reading difference is, it will save you a tow-truck ride home.
And no, I am not running an Orange box, I learned my lesson a long time ago.