I have the exact same problem with my Sallie Mae loans.
I have six loans that they are still reporting on all of my CR's that were consolidated in 5/1999. The status says "transferred to another office", but they are still reporting the tranferred loans, in addition to the consolidated loan as "open" on my Equifax report, and all are also being counted in my "total installment accounts" number.
At least one of my credit reports tells me that I have "too many installment accounts", so I am trying to get them to remove the consolidated loans from my CR. I will let you know if I am successful in getting these removed.
My advice would be to make sure that they are reporting these paid loans as "closed" and not still "open" as they are with mine because if they are showing as "open", depending on how many loans you have, it may lower your score, as it is with mine.
Hope this helps. Good luck.