Merged, Fraud, Duplicate re dated accounts.

Question regarding merged, fraud, duplicate, re dated accounts. Are furnishers of information allowed to list a duplicate account? I have one account that was purchased by another company and both companies have listed it on my bureaus. The buyer of the account dated the account when they purchased it and then gave it a new account number. What should I dispute this under? Do you know where in the FCRA this is listed as unlawful? According to one collection agent she stated that they can do this because there are no laws preventing it. Is that true?
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thats is true
but make sure they follow to the letter here
http://www.oskie.com/how-i-get-paid-collection-collections-account-removed-credit-report-completely.htm
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Okay, that letter scares me it’s so good I would never have thought to ask those questions. It may not get it removed but it will give them a hard time I’m sure. I will use it immediately.

Thank you for all your help.