Cannot redeclare db_connect()

Kode 

PHP Fatal error:  Cannot redeclare db_connect() (previously declared in /Applications/MAMP/htdocs/new_cms/core/functions/db.func.php:2) in /Applications/MAMP/htdocs/new_cms/core/functions/db.func.php on line 19

PHP kode 

 function db_connect() {
     global $config;
     $db;
     //Connect to database
     //Create PDO object. Syntax is driver:host=hostname;dbname=databasename, username, password
     try {
     $db = new PDO($config['driver'].':host='.$config['db']['host'].';dbname='.$config['db']['dbname'].';charset=utf8', $config['db']['username'], $config['db']['password']);
     $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION); //Error reporting
     //$db->setAttribute(PDO::MYSQL_ATTR_INIT_COMMAND, "SET NAMES utf8");
     }
      catch (Exception $e) {
         $_SESSION['messages']['error'][] = $e->getMessage();
         http_response_code(503);
         header('Location: maintenance');
         exit();
         //die($e->getMessage());
     }
     return $db;
 }