If the creditor still owns the debt, the reporting of a charge-off does not require any update of the debt balance to $0.
Update to $0 is required only if they sell the debt to another.
If the OC hires a debt collector to assist them in collection on the debt, the debt collector can also report, showing the amount they are atttempting to collect.
The OC account would also continue to show the current debt balance owed to them.
That is not double reporting of the same debt, as the OC reporting represents the debt balance, and the collection reporting represents the amount that the debt collector is authorized to conduct collection efforts on behalf of the owner.
Did you provde them a clear showing that the OC no longer owned the debt?
Alternately, you could contact the OC and remind them of their requirment (FCRA 623(a)(2)) to have promptly updated the balance upon their sale of the debt.
Hopefully, they will update without a renewed dispute.