Your bank has drastically oversimplfied the matter.
Multiple entries on a CR are proper, and happen all the time. They cannot be multiple entries of the same item of information, but any reporting done by the OC is based on delinwuencies and derogs that occured under your account with them, and any reporting done by a debt collector is a reporting of their collection activities. Apples and oranges.
They are not duplicate reportings.
You can dispute, but the burden in a dispute is to establish the inaccuracy of their reporting. Absent inaccuracies, disputes wont compel any favorable removal.
An OC can report monthly delinquencies. Then, they can decide to charge-off the bad debt, and report that as a CO. The OC then has three basis options for dealing with the uncollected debt. First,they can just continue to attempt collection on their own. That adds no additional credit reporting of derogs to your CR, since your account with them is closed. Second, they can assign collection assistance to a debt collector, while retaining legal ownership of the debt. From the date they assign collection authority to a debt collector, the debt collector can then report their collection activities to a CRA. The OC still reports a balance of debt owned under their account, and the debt collector reports the amount assigned to them for collection under their CA reportng. They may look like the same thing, and may even be the same amount, but again they are different, and thus not duplicate. Or third, they can just sell the debt, and be out of the picture.
I also disagree with the statement that you can only have one collection in your CR based on the same debt. Once the OC assigns collection authority to a debt collector, the debt collector can accurately report their collection, If the collection authority of debt collector 1 is then terminated, and the OC reassigns collection authority to a debt collector 2, that does not render the prior reporting by debt collector 1 inaccurate, or compel it deletion from your CR. Debt collector 2, now having debt collection authority, can accurately report that fact to the CRA. Nothing in the FCRA or the FDCPA compels the deletion of prior, accurately reported information based on subsequent activities of another party, such as the entry of a second debt collector into the mix.
