RealTest creates a folder called "Backups" within the folder where it was installed (by default c:\RealTest, so the folder is c:\RealTest\Backups).
Every time a script file (*.rts) is saved to disk, the previous version is automatically copied to the Backups folder.
If another file of the same name already exists in that folder, it is overwritten.
The same is done for the RealTest.ini file, which is where all of your user interface settings are stored and remembered.
The purpose of this Backups folder is to provide a way to go "one version back" if ever needed, or to retrieve a script in case it was accidentally deleted or overwritten.
It is also, of course, highly recommended to add your RealTest scripts folder to your list of folders to be backed up by whatever automatic local or cloud backup services you are using.
At the same time, it is advisable to exclude .RTD (data) files from such automatic backups, as they can be quite large and are easy to recreate.