error occuered when trying to create an existing tag, POST /tags

[crisone]

Fatal error: Uncaught exception 'PDOException' with message 'SQLSTATE[23000]: Integrity constraint violation: 1062 Duplicate entry 'fff' for key 'tag_name_unique'' in /var/www/html/app/library/Service/Db.php:67 Stack trace: #0 /var/www/html/app/library/Service/Db.php(67): PDOStatement->execute(Array) #1 /var/www/html/app/library/Service/Db.php(152): Service\Db->init('INSERT INTO`tag...', Array) #2 /var/www/html/app/library/Model.php(359): Service\Db->execute('INSERT INTO`tag...', Array) #3 /var/www/html/app/library/Model.php(266): Model->execute('INSERT INTO`tag...', Array) #4 [internal function]: Model->insert(Array) #5 /var/www/html/app/models/Facade.php(130): call_user_func_array(Array, Array) #6 /var/www/html/app/controllers/Tags.php(40): FacadeModel::__callStatic('insert', Array) #7 /var/www/html/app/controllers/Tags.php(40): TagModel::insert(Array) #8 [internal function]: TagsController->POST_indexAction() #9 /var/www/html/index.php(4): Yaf_Application->run() #10 {main}

thrown in /var/www/html/app/library/Service/Db.php on line 67