If you have duplicate client records for one client, you can merge their records by going to Patients -> Select the record from the patient list -> In the Information tab, you will see a Merge button (see below):

When selecting the record, choose the record you would like to have merged into ANOTHER record. 

When choosing the merge button, you are select the patient record that will become the PRIMARY record (see below):

Once selected -> click OK -> You will then be redirected to the merged record.