All twin engine setups from a manufacturer will have one counter rotating engine. It's almost always the port engine.
From what I understand, the trim tabs on the anodes of counter rotating motors are mostly inconsequential. Their purpose on a single engine installation is to counter the effect of the prop walk, which will tend to cause your stern to "walk" to starboard with the forward rotation of the propeller, conversely causing your bow to want to turn to port. With a twin engine, counter rotating installation, the opposite rotation of the propellers will cause the prop walk to essentially cancel out, and the boat should track straight regardless of the trim tabs on each engine. I've even seen where they're eliminated entirely.