To duplicate a file, click on the three dots to the right-hand side of the file and select Make a copy. This creates a copy of the file named "Copy of <file name>" in the same folder as the original file.
You can then move the copy to your chosen location. Again, click on the three dots to the right-hand side of the file. Select 'Move to....' and a new menu will allow you to come out of the folder you're in and to select a new one.
Select Move Here once you've found the location you want.