Plugin is creating this error: [Wed Jun 24 23:36:43 2015]

Plugin is creating this error:

[Wed Jun 24 23:36:43 2015] [error] [client 98.237.148.255] PHP Fatal error: Cannot redeclare class ms_plugin in /nas/wp/www/cluster-10983/jasonfox/wp-content/plugins/membership/membership2.php on line 151, referer: http://www.jasonfox.me/wp-admin/plugins.php?plugin_status=all&paged=1&s