docs: def _validate_duplicates(self):
          """
          Ensure we're not creating a device that already exists
          Runs only when the DeviceConnector object is created, not when is updated
          """
          # if connector is being created right now
          if not self.id:
              duplicates = []
              self.netengine_dict = self.netengine.to_dict()
              # loop over interfaces and check mac address
              for interface in self.netengine_dict['interfaces']:
                  # avoid checking twice for the same interface (often ifconfig returns duplicates)
                  if interface['mac_address'] in duplicates:
                      continue
                  # check in DB
                  if Interface.objects.filter(mac__iexact=interface['mac_address']).count() > 0:
                      duplicates.append(interface['mac_address'])
  
              # if we have duplicates raise validation error
              if len(duplicates) > 0:
                  mac_address_string = ', '.join(duplicates)
                  raise ValidationError(_('interfaces with the following mac addresses already exist: %s') % mac_address_string)