How to select at least one duplicate value of my JTable?

I try to establish a condition that determines that at least that I have selected at least one duplicate value in my JTable, the information in the JTable looks like this.

I have something of this style that fills the JTable

try {            
    Connection con = null;
    con = getConection();
    PreparedStatement ps;
    ResultSet res;
    ps = con.prepareStatement("EXEC PA_ENTREGA_A_RECEPCION " + quincena.getSelectedItem() + "," + ano.getSelectedItem());
    res = ps.executeQuery();
    Resultado.clear();
    while (res.next()) {
        Object[] resu = new Object[2];
        resu[0] = res.getString(1).trim();               
        resu[1] = false;
        Resultado.add(resu);
    }
    int arregloTam = Resultado.size();
    Object[][] data = new Object[arregloTam][2];
    for (int i = 0; i < arregloTam; i++) {
        data[i] = Resultado.get(i);
    }
    DefaultTableModel tb_model = new DefaultTableModel(data, columnNames);
    jTable1 = new JTable(tb_model) {
        private static final long serialVersionUID = 1L;

        @Override
        public Class getColumnClass(int column) {
            switch (column) {
                case 0:
                    return String.class;
                case 1:                            
                    return Boolean.class;
                default:
                    return String.class;
            }
        }

        @Override
        public boolean isCellEditable(int row, int col) {
            switch (col) {
                case 0:
                    return false;
                case 1:                           
                    return true;
                default:
                    return false;
            }
        }
    };            
} catch (SQLException e) {
    JOptionPane.showMessageDialog(null, "Seleccione una Qna");
} catch (Throwable ex) {
    JOptionPane.showMessageDialog(null, "Existen Faltantes de R3");
}