From time to time you might accidentally duplicate a customer which can cause confusion when it comes to creating a new invoice or allocating an invoice to a receipt on an imported statement. The merge facility gives you the option to combine the transactions from both customers and remove the duplicated customer.
Please be careful when merging contacts as changes are irreversible. If in doubt, create a restore point first on Tools > Export > Backup.
Navigate Contacts > Customers
Click the Merge contacts button.
Select the duplicate customer in the Merge this contact drop down box and the primary customer in the Into this contact drop down box, then click Review.
You will then be able to review the data allocated to each customer. To confirm select Merge.