Package the original in your Workflow Manager, by clicking (highlighting) the project you want to copy, then click "Package":
Then click "yes" to open the directory:
Then open the .package file that you just created:
Then give it a different name:
That should hopefully get you where you need to be. Remember to publish the copy when you're ready. When using this method, you'll need to check the publishing properties to make sure you aren't overwriting anything. for example, when I go to publish the example I ran through for these screenshots, on the first publishing screen, I just adjust the Virtual Directory name:
That should do it! Let me know if you need more info.