Rather than manually building a duplicate credential, you can use the Copy Credential Tool.
Here's how it works:
Under Administration tab, select Manage Credentials. Then click the Credential you wish to copy.
Click the gear icon to open Credential Options.
Scroll to the bottom and click Copy.
Name your new credential, and check the box if you wish to copy your enrolled users into the new credential as well. Then, click Save.
Your credential has been copied. All settings, alerts, topics, course/activity requirements, and users have been successfully replicated in the new credential.