I was originally doing this 'already has badge' substring check in order to make a more user-facing error message, but I ended up deciding to not even count it as an error condition if they already have the badge.  Instead it just opens the success/push-to-backpack window if the user either succeeded in claiming the badge, or already had it.  I figured that there's really no reason to prevent a user from using the "push to backpack" functionality if they do, in fact, have the badge.