In older versions of Microsoft Dynamics NAV, the most that users can do with duplicate customer, master data with transactional posting, is to zero out its balance, move its balance to the original or correct customer, and block the duplicate customer.  This results in many needless customer records, causing confusion with end-users.  In Dynamics 365 Business Central, duplicate customers can now be merged using the Merge With functionality allowing the correct customer to be retained while the duplicate deleted.  Other master data such as Vendors and Contacts has the ‘Merge With’ function.  This blog post shows how Customer master can be merged.


A Dynamics 365 Business Central user, receives a call from a new contact from a Customer to place an order for an item.  The user then created a new Customer master data, linked the contact to the customer, and then raised a Sales Order and posted it.  Later on, the user found that he has created a duplicate customer master data.  The new contact should be linked to the original customer data.

How to Merge Customer Data

In the Customer list below, we will see that the original Customer No. 10000 has a higher balance and the duplicate Customer No. 10005 has only a balance of $1,000 which was the first sales order posted.  The correct contact, Mr. Bill Smith, has been set to the duplicate customer.

Merging duplicates in MS Business Central

We will now merge the data of the duplicate Customer 10005 to the original customer 10000.  Open the Customer card of the original customer and click ‘Actions > Functions > Merge With’.

The Merge Duplicate page will open up showing the Current customer which is the original customer.  In the Merge With field, we will enter the customer no. of the duplicate customer.

Merging duplicates in Business Central

In the Fields FastTab, this is where we can override the field value of the current/original customer with the duplicate customer.  As the new contact needs to be linked to the original customer, we will be ticking the Override checkbox for the Contact field.

Merging duplicates in Business Central

The Related Tables FastTab shows the listing of all the tables that are associated to both customers that will be merged. These are mostly transactional tables.

Merging duplicates in Business Central

After updating the fields that need to be overridden and reviewing the related tables that will be affected by the merging process, we can now hit the Merge button at the upper left corner of the page.  In some cases, conflicts may occur after hitting Merge.  These conflicts should be fixed by hitting the Resolve conflicts before merge link, click View Details, and clicking Remove Duplicate or Rename Duplicate.

Merging duplicates in Business Central

Merging duplicates in Business Central
We can now run the Merge function again after resolving the conflicts.  A message will pop out as below which warns the user that the merging cannot be undone.  This process is irreversible because the duplicate customer will be permanently deleted and the data will be combined to the original customer.

If we go back to the Customer list, we will see that the duplicate customer has been deleted.  The balance of the original customer has also increased by $1,000 and the relevant transactional history tables such as Posted Sales Shipment and Posted Sales Invoices have been updated with the posted data of the duplicate customer.

Merging duplicates in Business Central

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