I just discovered this hilarious illustration from the Illustrated Police News, which is a self-explanatory sensational Victorian publication. Sadly, I've been trawling the electronic copies my university has access to and I can't find this story at all, so I have no date and no context.
That said, in my search I found another story (from Saturday, July 19, 1890; Issue 1379), this time with context.
This took place in a circus traveling through Paris. Two of the acrobats decided to resolve their differences through a duel. They both fired, no one was hurt, honor was restored.
Unfortunately, they neglected to realize that the monkeys were watching, and had been trained to perform soldiering exercises. Thinking they were being taught a new routine, they picked up the pistols (which I guess the acrobats just left lying around), loaded them themselves, and imitated what they had seen. The monkeys both died instantly.
Just because I don't buy this story for one second doesn't mean it's not awesome.