While logging into your service’s account, try different codes and save only the one that works, deleting the others. Don’t worry – deleting one code won’t delete all the others.
Remember, you can always use the additional description feature for deferring tokens to the same service.
If you’ve deleted a wrong code by accident, don’t worry. Simply go to Settings, then Trash and all the deleted codes will be there. Now tap on three dots on the right of the code and tap Restore. That’s all, the code will now be back in the Tokens list and ready to use.