In Permalinks v1.05, the code that updates the old permalinks are on line 219-221 and looks like this:
// mark all other matching permalinks for this record as old
$where = mysql_escapef("`tableName` = ? AND `recordNum` = ? AND permalink != ?", $tableName, $recordNum, $permalinkText);
mysql_update('_permalinks', null, $where, array('old' => '1'));
I didn't mention the exact lines/code as I'm not sure what version you're using.
Cheers,
Daryl Maximo
PHP Programmer - interactivetools.com