code: @Override
      public boolean add(Object o) {
          ConnectorProperty connectorPropertyToAdd = (ConnectorProperty) o;
          String nameToAdd = connectorPropertyToAdd.getName();
  
          ConnectorProperty connectorProperty = null;
          String name = null;
          Enumeration<Object> e = this.elements();
          while (e.hasMoreElements()) {
  
              connectorProperty = (ConnectorProperty) e.nextElement();
              name = connectorProperty.getName();
              if (name.equals(nameToAdd)) {
                  if (tc.isDebugEnabled()) { 
                      String value = (String) connectorPropertyToAdd.getValue(); 
                      if (!value.equals("")) { 
                          if (name.equals("UserName") || name.equals("Password")) { 
                              Tr.debug(tc, "DUPLICATE_USERNAME_PASSWORD_CONNECTOR_PROPERTY_J2CA0103", new Object[] { (ConnectorProperty) o });
                          } else {
                              Tr.warning(tc, "DUPLICATE_CONNECTOR_PROPERTY_J2CA0308", new Object[] { (ConnectorProperty) o });
                          } 
                      }
                  }
                  return true;
              }
  
          }
  
          return super.add(o);
  
      }
docs: override the Vector add method to not add duplicate entries.  That is, entries with the same name.