Dates appended more than once to backup file names

Interesting to note that this seems to happen when you have multiple scheduled backups that run at the same time.

First scheduled backup: DaveReid-2011-11-08.mysql.gz
Second: DaveReid-2011-11-08-2011-11-08.mysql.gz
Third: DaveReid-2011-11-08-2011-11-08-2011-11-08.mysql.gz

I believe the problem is in backup_migrate_perform_backup() which alters $settings by reference and hence $settings->filename is altered every time.

/**
 * Perform a backup with the given settings.
 */
function backup_migrate_perform_backup(&$settings) {
  ...
  if ($settings->append_timestamp && $settings->timestamp_format) {
    // Second and third time this statement is called it continues to append
    $settings->filename .= "-". date($settings->timestamp_format); 
  }
  // Tokens have already been replaced the first time, so this does not affect the file name.
  $settings->filename = _backup_migrate_clean_filename($settings->filename); 
  ...