Hey Jim! Welcome to the WL community :)
Trogatog, is that an actual game that you had? This is clearly going wrong somehow. Can you send me the link?
Yup, this actually happened. I don't have the link anymore, it was a while ago, I just came across the pic in my pic folder yesterday and remembered I wanted to post it. With the game settings the way they are, this can very much happen (100% luck). I think I linked a game a couple pages ago where an opponent stack of 6 attack into a stack of 7 of mine and the resulting armies left were in favor of the opponent.
I want to say this happens all the time, but in reality, they happen in the games we lose, which makes them more memorable. Looking at my history, when I stack armies just so they survive an attack, 75% of the time it works as expected.