Google Authenticator 2.0 was released three days ago to support an all-new design and iOS 7. Unfortunately, a bug caused the update to delete accounts, causing an inconvenience for many users (including yours truly). The app has now returned to the App Store for download and it restores your previously deleted entries.
What’s New in Version 2.0.1
Restores entries that were not displayed due to a bug in version 2.0.
Support for retina display and iPhone 5.
Improved user interface.
Minor bug fixes.
Improved accessibility support.
If you already re-added your accounts, this update restores your old accounts so now you’ll have duplicates. Have fun figuring it all out!