Two memcached servers for sessions

Hello,
Im using latest CI3.

I have started two memcached instances - 127.0.0.1:12345 and 127.0.0.1:12346

Now in my config.php I have:

PHP Code:

$config['sess_driver']  = 'memcached';
$config['sess_save_path'] = '127.0.0.1:12345,127.0.0.1:12346'; 


my php.ini:

Code:

memcached.sess_number_of_replicas = 2
memcached.sess_consistent_hash = on
memcached.sess_remove_failed_servers = on
memcached.sess_server_failure_limit = 3
memcached.store_retry_count = 2

Now when both of the memcached instances are on, it works.
When I turn off the first and keep the second on, it works.

But when I turn off the second and keep the first on, it does not work - it tries for 12 seconds and then I have this error:

Message: session_start(): Failed to read session data: user (path: c:/wamp64/tmp)