Yeah, intercylinder robbing, especially with a big overlap cam. VE suffers on the second cylinder of the shared pairs. You can time the fuel, but the air is going to take it's own best path.
With a Winfield design, you get an intake pulse every 360 degrees per intake port, whereas in a 1342, the second cylinder of the shared port gets short changed, 180 - 540, which is compounded by a long duration, big overlap cam.
If you have separate exhaust ports for each cylinder, the Winfield design is pretty hip, but it does require extra care in balancing. I'd thought about it for the 970, but with only 3 exhaust ports, I'd wind up with scavenging and reversion issues on the 2-3 exhaust strokes - the two cylinders which tend to run warmer, anyway.