The system is deterministic but it seems it is not because there is a lot of parameters you can't know...
For 1 vs 1, without other units, you always get the same result.. euh.. that said, there is a first parameter modifying this result.. the time scale.
The geometry of unit position is important, so changing the time scale can modify the distance between the units, so the result of casualties.
BTW, in a real battle, it's not 1 vs 1, but 100 vs 100 with a lot of interactions.. each calculus is deterministic, but you can't predict the result because you don't know the events modifying the calculus...
I find it's not the best to have an elite regiment losing a fight against a regiment of line with a dice... because the elite always wins except if the external conditions infers a problem about its behaviour.
I hope it's clear.
JMM