Do Diesel Injectors Usually Group Fire During Cranking?

I don't know for certain, but I would think no compression ignition (CI) engine should batch fire injectors. The reason is how the CI engines work. You don't want fuel in the air which is being compressed, or it could spontaneously combust at any time. You want the combustion to happen at exactly the right time, akin to spark timing in an spark ignition engine. If you batch fired, there would be fuel in the intake charge, which means it could burn at any time the temperature got hot enough to burn. For this reason, I'd say it is nearly impossible for a CI engine to be batch fired.

As far as what you're observing ... are you positive it's not a 2-stroke engine? I don't think it's a common way for diesel engines to operate, but I do know they exist (Detroit Diesel 71 series engines were 2-stroke engines). A 2-stroke engine would fire during every revolution. If it is indeed a 4-stroke (most likely), then there's probably a problem in the injection system.

You mentioned this was without ignition, or at least it sounds like it. Since it isn't actually igniting, maybe the PCM wants to do a power stroke on every TDC?