After running twice,
python run.pydata.json is updated with data from dummy.json (from to_add/ folder). When the script is run a second time, a backup of data.json is made before content from dummy.json is added to it, stored in backup/ folder as backup/data.json.
If data.json was updated wrongly and you want to go back to the original data.json file without added content from to_add/ folder, replace root directory data.json with backup/data.json and run to generate the original dex (without added data):
python run.py