How do I duplicate an appengine app
Do you have more than one google account?  I have found that app engine does unexpected things when you are logged into more than one google account at a time.
I suggest logging into only a single google account and trying the operations again.
I want to backup my python app and restore it to a different app on Appengine.  In the Application Setting Page, under Duplicate Applications, I add a new application identifier.  
When I click the Duplicate Application button, I get this error: "The developer does not own the app id being forked".
Further research indicates that this seems to be a bug, but that a workaround is to send an email invitation to the other email addresses in my Google account to add them.  
I am able to send those emails from the Permissions screen by clicking a button and inserting the email address. When I click link in the email that is sent, it opens My Applications, listing all my apps, instead of a confirmation that my response.  It appears to open the wrong page.
In the Permissions page, the email address still shows Pending after about 10 hours.
Is there a simple way to duplicate an application?