Deleting duplicate services and duplicate contacts work in much the same way.
Select the service or contact that you wish to remove and try to
delete it. At this point, it will check to see if that Contact or
Service is associated with an existing appointment. If it is then you
will be prompted to merge that contact or service with an existing
contact or service.
For Contacts, any details that are associated with the contact to be deleted will be added to the retained contact.
For Services, all the appointments that are currently associated with the service to be deleted, will be changed so that they are now associated with the retained service.