$query = $_SGLOBAL['db']->query("SELECT itemid FROM ".tname('spacetags')." WHERE tagid IN (".simplode($tagidarr).") AND itemid<>'$itemid' $sqlplus ORDER BY itemid DESC LIMIT 0, $num");
替换为
$query = $_SGLOBAL['db']->query("SELECT distinct itemid FROM ".tname('spacetags')." WHERE tagid IN (".simplode($tagidarr).") AND itemid<>'$itemid' $sqlplus ORDER BY itemid DESC LIMIT 0, $num");