Greg:  I never knew about LL rounds, nor special markings on shotguns, and it makes sense.  But I think that I could easily have made the same mistake as that officer.  Were I to have only a regular shotgun available, and loading non-lethal rounds, I would still load a slug as my last shot, just in case the bear charged.  That is one possible answer for the officer's mistake.  He simply lost count of how many rounds remained.  A very angry Brown Bear can be distracting.