Okay, that would explain it then, I suppose.
In other words: They aren't very useful at the moment and won't be, unless higher laser techs would be made available to them, seeing as they stop at extreme x-ray.
In my current game, a strenght-36 warhead is cut down to strenght-22 and two laser heads once I check the box. Now in theory, if you take overall damage with the different damage profile, that would be superior....but without knowing exactly what the effect of having 2 laser heads is, it's a bit of a gamble. You're either smashing through 8 layers of armor, or you're sandpapering it a bit deeper than usual at 3 layers. The difference in effect is quite big.