[need help please] I want to store session data in multiple memcache server.

Hello, Im trying store session in multiple memcache server, why session only store data in one of memcache server ? but if I'm comment one of them, it works.

$driver_session = new \Phalcon\Session\Adapter\Libmemcached(array(
        'servers' => array(
                 /*array(
                     'host' => '192.168.0.105', // mandatory
                    'port' => 11211, // optional (standard: 11211)
                     'weight' => 8600, // optional (standard: 8600)
                 ),*/
                 array(
                     'host' => '192.168.0.101', // mandatory
                     'port' => 11211, // optional (standard: 11211)
                     'weight' => 8600, // optional (standard: 8600)
                 )
             ),
             'client' => array(
                 Memcached::OPT_HASH => Memcached::HASH_MD5,
                 Memcached::OPT_PREFIX_KEY => 'prefix.',
             ),
             'lifetime' => 3600,
             'prefix' => 'ini_session_')
         );

 $driver_sesion->start();