Backup Files
The program has a backup security feature to protect your files from being accidentally lost. It creates backup files when you try to save a document under a name of an existing file. Your new document is saved with the name you have specified, and it automatically renames and saves your old file.
The program renames old files by default. Enable or disable this feature by selecting Preferences in the File menu and checking or clearing the Create backup files field in the General Tab.