Duplicate keys

Found in logs, this may prevent the plugin cache data properly.

[Fri Dec 05 07:29:54 2014] [error] [client 2001:16d8:cc8b::3] WordPress databasfel f\xc3\xb6r Duplicate entry '2001:16d8:cc8b::3' for key 'ip' f\xc3\xb6rfr\xc3\xa5gan INSERT INTO `wp_dnsblcache` (`ip`,`resolvetime`,`resolve`) VALUES ('2001:16d8:cc8b::3','2014-12-05 06:29:54',0) skapat av require_once('wp-load.php'), require_once('wp-config.php'), require_once('wp-settings.php'), include_once('/plugins/tornevall-wp-dnsbl/tornevall-wp-dnsbl.php'), require_once('/plugins/tornevall-wp-dnsbl/tornevall-wp-dnsbl-functions.php'), t_dnsbl->testip