$qry = 'INSERT INTO notice_inbox (user_id, notice_id, created) ' .
'SELECT user.id, ' . $this->id . ', "' . $this->created . '" ' .
'FROM user JOIN subscription ON user.id = subscription.subscriber ' .
- 'WHERE subscription.subscribed = ' . $this->profile_id;
+ 'WHERE subscription.subscribed = ' . $this->profile_id . ' ' .
+ 'AND NOT EXISTS (SELECT user_id, notice_id ' .
+ 'FROM notice_inbox ' .
+ 'WHERE user_id = user.id ' .
+ 'AND notice_id = ' . $this->id . ' )';
if ($enabled === 'transitional') {
$qry .= ' AND user.inboxed = 1';
}