If you are doing a "Save as" and the filename already exists in the folder, it's a good practice to NEVER wrigth over that existing file. Instead select the existing file in the "Save as" dialog, by clicking on it (once) and hit Delete on the keyboard.
Then you can get the old file back from the trashcan if you did something wrong.
You can also rename existing files and change fileproperties in the very same "Save as" dialog.
This is not only for IronCAD, but for all Windows program use.