If you do not have automation you can manually merge the contacts in the Bulk Merge Contacts List.
1.Click Bulk Merge on the tool bar.
2.Click Yes after you have read the dialogue window, making sure the merge ref is the one you have uploaded and that this process CANNOT be reversed.
3.Click Yes to accept the user that will be recorded for the Audit Trail.
If there are any errors they will be listed on the Bulk Merge Contacts form. In the following example the same serial number had been copied more than once into the spreadsheet and also the same serial number was the master and duplicate.