[PvK]

It is sort of a Proportions issue. It is probably because the Abbidon haven't researched ECM fast enough to get an ECM device which gives a better bonus than their best engines. So when the SE4 AI makes a design that calls for a defensive device, it thinks the best one is an engine, and adds that, even though it won't add any defense because it already has engines of the same type, so the effect won't stack. I would rate this as a very minor advantage to the AI, which doesn't compensate for the AI's lack of ability to optimize engine type mixes the way micromanaging perfectionist humans can. Not a big deal.

A side issue for perfectionist AI modders: When making AI files, it's often not worthwhile to put ECM on transports.

PvK