How to add two Jpanels to a JFrame?

Question

Java

How to add two JPanels to one frame? I do so

import javax.swing.*;
import javax.swing.border.TitledBorder;
import java.awt.*;

public class ColumnOne extends JFrame {

    public ColumnOne(){
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setExtendedState(MAXIMIZED_BOTH);
        setTitle("Rails");
        week();
        setVisible(true);

    }

    public void week(){
        Object[] headers = {"1", "Lesson"};
        Object[][] monday = {{"1", "English"}, {"2", "Algebra"}};
        Object[][] two    = {{"1", "Physic"}, {"2", "Kazkah"}};

        JTable jtMonday = new JTable(monday, headers);
        JTable jtTwo = new JTable(two, headers);

        JPanel weekClassOne = new JPanel();
        weekClassOne.setBounds(0,20, 400, 650);
        weekClassOne.setBackground(Color.DARK_GRAY);
        weekClassOne.setBorder(BorderFactory.createTitledBorder(BorderFactory.createEtchedBorder(), "1", TitledBorder.CENTER, TitledBorder.TOP));
        weekClassOne.add(new JScrollPane(jtMonday));
        weekClassOne.add(new JScrollPane(jtTwo));

        getContentPane().add(weekClassOne);

        JTable jtMondayCls2 = new JTable(monday, headers);
        JTable jtTwoCls2 = new JTable(two, headers);

        JPanel weekClassTwo = new JPanel();
        weekClassTwo.setBounds(0,20, 400, 650);
        weekClassTwo.setBackground(Color.PINK);
        weekClassTwo.setBorder(BorderFactory.createTitledBorder(BorderFactory.createEtchedBorder(), "2", TitledBorder.CENTER, TitledBorder.TOP));
        weekClassTwo.add(new JScrollPane(jtMondayCls2));
        weekClassTwo.add(new JScrollPane(jtTwoCls2));

        getContentPane().add(weekClassTwo);



    }
}

But I draw like this weekClassOne inside weekClassTwo. Why is this happening, what is wrong?