What happens to saved data for different versions

Just tested it, the data files from jar is copied every time it loads to override the older versions, but if you are running two versions at the same time, the latter's will be shared in two bots.

Maybe some mechanism to separate files from different versions helps. E.g. Using a version number prefix of each file, either from jar or created on the fly.

And for saved battles, I'm considering using the pairing instead of the opponent as names.

And instead of version numbers, something similar to serialVersionUID may also be used as prefix.