No, it isn't normal.
Possibly cousin's file was split at some point and when it was joined back, the accounts were duplicated.
I assume you mean duplicated as in the same creditor reporting the same account multiple times and not multiple CA reporting the same account.
A lot of work to be done and I'd do the disputing on paper via mail or fax. I think I would send a current copy of my report and highlight the mistakes along with a cover letter.
I'd say all highlighted accounts are duplicates, please remove. Just remember to leave 1 of the accounts from each duplicated set un highlighted.
