This project is not covered by Drupal’s security advisory policy.
Already in redirects authenticated users who attempt to visit the login, user registration, or password reset URLs to an alternate destination instead (the /user page by default). This prevents authenticated users from getting an Access Denied error message. Optionally, the module can display a "You are already logged in" message when redirecting users.
The issue this module addresses has been fixed in Drupal 7, see.