Thanks for the question.
It has happened in the past with certain Payment Distribution Agencies that they continued disbursing payments even though the account has already been paid in full.
To determine if you paid to much to one creditor I would advise that you ask them for a complete recon of the account that reflects each and every payment that they allocated to the account. Also ask for a complete distribution statement from the Payment Distribution Agency so you can see all the payments made to this specific creditor from day one.
If you paid to much on this account they will have to refund you immediately.
If you do not have direct contact with your Payment Distribution Agency your debt counsellor MUST assist you to get the required detail that will enable you to do a full recon on the account.