When duplicate customer profiles are identified and merged, either manually by the seller or using automated detection, the existing profiles are merged into a single profile that is assigned a new ID.
If you specify the ID of a customer profile that was deleted in a merge operation, the Customers API returns the new customer profile. For example, suppose customers A and B are merged and a new customer C is created. If you call RetrieveCustomer using the ID of customer A or B, the Customers API returns customer C. 