With a key?
Only one chest should need a key - at most, I cannot quite remember if it does, or if instead the door to the room it is in needs a key. I seem to remember finding two keys together - one unlocks something important, and the other goes with a singleton from somewhere else to open a double-locked door to somewhere nice but not important.
What I have discovered is that several of the chests, spread over about three different rooms, are all one and the same - I call that a bug. Maybe you've discovered a variation of that bug.
Unless, like skull piles, some of the chests need expert perception to open? All my characters already had that for a chance to duck if my disarm trap fails.
Post edited August 19, 2018 by RSimpkinuk57