From the docs:
Note that a user’s Cloud account is “universal” across all apps that use
Corona Cloud, so it’s possible that a user has already registered an
account from another app.
The question here is how will the user know he already has a Corona Cloud User account or that your app uses Corona Cloud ?
This is a question for the developers that will use Corona Cloud User management in their apps, but suggestions from Corona team are more then welcome.
Regards,
Damir.