The second number is the number of pending submissions for that topic.
If you don't want it, you can switch it off in config.php:
Text Formatted Code
// Show the number of stories in a topic in Topics Block
$_CONF['showstorycount'] = 1;
// Show the number of story submissions for a topic in Topics Block
$_CONF['showsubmissioncount'] = 1;
bye, Dirk