From what we know, This actually happens because of Previous save files
The reason it only happens with DarkCloud makes a custom game, is because DarkCloud had a custom Difficulty save in 0.1.0
The Game save structure and place changed this version, but it still creates and references many files in the old location, and because of this, it seemed to largely cause issue when a player tried to make the same difficulty in the new version - They are, after all, both initially referred with the same file-name
Version 0.1.1 engine/game is trying to create a "new" save though
While the game is seeing and reading an "already created" save, with conflicting data
While Paul, Would have, maybe normal difficulty save, or maybe one of each non-custom difficulty.
This is not the only way we've seen recreate the issue, but, its the most prominent way
( I say we, I mean all users)