[jcl]

So, it seems that the intent of the code is to add two parallel, invisible kill beams to augment the main beam. The nature of the bugs are such that the added beams are positioned in roughly the right place, for a certain axis-aligned view.

I’d guess that the feature was tested manually in such a view, and seemed to work OK. And that the feature was subtle enough of a behavior tweak that no one noticed that it didn’t work correctly in most other situations, since the main, visible beam worked correctly, and no one could see it killing enemies behind walls.