I don't believe this is creating a duplicate of the active file.
When you save it with a different name the original will be abandon in its last saved state and
you will automatically now be working with the newly named and saved file in the current state.
If that is your desire, don't close the active workbook.

OR

Are you saying that you can't find the newly saved file after closing it ?
If so, those empty double quotes may be the issue.