Using the mansion file isn't required at all, just gives a few more options when creating your initial character (those 4 in the 2nd column that are blank in the above screenshot being those options). If you want those options you must rename his mansion.tscn file but i would recommend saving yours elsewhere first. Can also leave the duplicates in the folder they're in, they won't hurt anything. If you don't use his mansion file it will just automatically generate those stats for you.