FULL PRODUCT VERSION :
java version "1.8.0_66"
Java(TM) SE Runtime Environment (build 1.8.0_66-b17)
Java HotSpot(TM) 64-Bit Server VM (build 25.66-b17, mixed mode)


ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows [Version 10.0.10586]

A DESCRIPTION OF THE PROBLEM :
The icon appears twice, on the left AND the right when you change the default position in a JMenuItem using setHorizontalTextPosition() with Windows Look and Feel.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
See self contained test below. 

Or just create a JMenuItem with an icon and text, then change the default position of the icon using setHorizontalTextPosition(SwingConstants.LEFT)

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
Can change the icon position in a JMenuItem using setHorizontalTextPosition() 
ACTUAL -
The icon appears twice, on the left and the right side of the JMenuItem

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.image.BufferedImage;

import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.SwingConstants;
import javax.swing.UIManager;


public class WinMenuItemIcon {

	public static void main(String[] args) {
		
		//NOTE: Bug happens with Windows L&F
        String name = UIManager.getSystemLookAndFeelClassName();
        try {
			UIManager.setLookAndFeel( name );
		} catch (Exception e) {
			e.printStackTrace();
		}

		JFrame frame = new JFrame();
		frame.setTitle("Test");
		frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		
		JMenuBar menuBar = new JMenuBar();
		JMenu menu = new JMenu("Menu");
		
		ImageIcon icon = createIcon();
		
		JMenuItem menuItem = new JMenuItem("Command", icon);
		menuItem.setHorizontalTextPosition(SwingConstants.LEFT);
		menu.add(menuItem);
		menuBar.add(menu);

		frame.setJMenuBar(menuBar);
		frame.setPreferredSize(new Dimension(500, 500));
		frame.pack();
		frame.setVisible(true);
	}
	
	protected static ImageIcon createIcon() {
		BufferedImage bi = new BufferedImage(25,25,BufferedImage.TYPE_INT_ARGB);
		Graphics g = bi.createGraphics();
		g.setColor(Color.RED);
		g.fillOval(0,0, 25, 25);
		return new ImageIcon(bi);
	}
	
}




---------- END SOURCE ----------

CUSTOMER SUBMITTED WORKAROUND :
Don't use Windows Look and Feel. Works fine with default Java look and feel.