When found, it has

0 (zero) charges of:

Bull's Strength 1charge/use Shield 1charge/use Cat's grace 1charge/use

It's possible that the item was used before you got your hands on it.

Since an NPC dropped it, I'm pretty sure that wasn't the case. I could be wrong - it's not the first Minor Monkish Amulet with 0 Charges I found.

nah, NPCs use the objects in their inventory all the time... which is why there was a problem a while back with undead committing suicide using purple crystals on themselves.

I found another MMA in a Chest, during the Portal Quest. All locks & traps were still there, so I assume we were the first to do it. Henceforth, no one could have dropped it in. Has anyone at all found a MMA which did, in fact, had charges left?

It did need to be fixed, but I'll reiterate that NPCs are quite capable of using up charges on items, leading to that irritating issue with the undead blasting themselves with healing items. Fixed in v841.