Ok so I recruit a mercenary for 2000gp.
And as I wanted that both my main character and my mercenary has a custom portrait. I have import a new image. And… The portrait of both my character has changed. I don’t remember if that was immediatly or later (I didn’t noticed).
So I tried to push the bug, I began a new adventure and I created a new character with new imported portrait. Then I loaded my previous savegame and… Shit… All my characters have changed their portraits in all custom portrait in all savegame.