If you would like to duplicate a contact within Synaptic Comparator (maybe for a partner who lives at the same address etc..), click on the Contacts button in the left hand menu:
Click on the name of the client you wish to duplicate in the Contacts column, then click duplicate from the top menu:
The details of the client you have duplicated will now appear on screen, minus the forename and date of birth.
Once you have changed the details as appropriate and completed the two missing mandatory fields (forename and date of birth), click on save to create the new client, or cancel if you decide not to create a new client.