To make a backup of your work, do not make a copy of a drawing in your current project folder. This will be seen by the project database as a new drawing, and everything on the drawing will be duplicated. This often leads to doubled loads on panel schedules or incorrect quantity counts.
The correct way to back up a project is to copy the entire project folder to a new folder. The easiest way to do this is with the Copy or Backup Project command.
Ribbon: DM->Utilities-> ->Copy or Backup Project
Pulldown Menu: DM->Utilities->Copy or Backup Project
This will copy all of the drawings and the database file for the current project to a new folder. You can also copy the files manually if you want to control which files are copied.