Judging by the numbers I'd say those are Mediacloqued disks that SC put out for a while. If SC re-issued those disks you can get them to replace them for about $5 S&H (call ahead for instructions and availability).
The disks that you can't get the last track ripped are multisession disks that many manufacturers put out. You can use Microstudio to rip those, and/or Hoster 3.3 tentatively due by the end of the year will rip them as well
You can do a forum search for mediacloaque and multisession to get more info
Sam
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