JTable Duplicando Coluna!

public void tabela(){
                   
          DefaultTableModel modelo = new DefaultTableModel();
            JTable grade;
                  
                  JScrollPane painel = new JScrollPane();
                  grade = new JTable(modelo);
                 
                   modelo.addColumn(null);
                  modelo.addColumn("NOME");
                  modelo.addColumn("VALOR");
                
                  grade.getColumnModel().getColumn(0).setMinWidth(0);
                  grade.getColumnModel().getColumn(0).setMaxWidth(0);
                  grade.getColumnModel().getColumn(1).setPreferredWidth(300);
                  grade.getColumnModel().getColumn(2).setPreferredWidth(150);
                  grade.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);
                  grade.getTableHeader().setReorderingAllowed(false); 
                  painel = new JScrollPane(grade);
                  painel.setBounds(6, 315, 500, 250);
                  this.add(painel);
                  
                  grade.addMouseListener (new MouseAdapter () {
                  public void mouseClicked (MouseEvent e) {
            
                 recuperardados();
                  nome=t_nome.getText();
       
        codigo= t_cod.getText();
    
       }
      });
    
              }