We are seeing situations in which we have sent a final credit letter to a customer on a Reg E dispute and then the merchant also credits the account. Are we allowed to send a letter stating we are debiting the account the amount of the dispute since credit was received twice? We have already made the customer "whole", the second credit is pure profit for them.

I hate when this happens. The customer basically started a claim with the bank and with the merchant.

It is my beliefe that once you send the closed letter the claim is considered closed and you can't go back and reverse your credit. In time the merchant will probably reverse the credit issued directly to the customer since they will be debited by the chargeback also.

In my mind I have to keep my boundries clear on REG E compliance and what is "fair". Stop looking at accounts after the claim is closed! LOL

You can't proactively perform the debit, but you are not prohibited from bringing the facts to the consumer's attention.

Here's what you can do. Send a letter or make a call that:
1) Details how you issued credit because of the claim that was previously made;
2) Explains how a merchant credit has now come through that "appears" to resolve the dispute (the credit may be for the same amount but you don't know why the credit is there - it may be for another purchase or even for a purchase on another card).
3) You are requesting that the consumer contact you via phone and/or mail in order to discuss the dual credit.

Provide as much detail as possible (dates, amounts, ect.) Mention nothing about wanting to re-debit the account. A reasonable person would contact you to have the dual credit removed. If the consumer decides to not contact you, then there isn't anything you can do.