有没有办法防止ttk OptionMenu回调触发两次？

import tkinter as tk
from tkinter import ttk

def callback(*args):
    print("OptionMenu selected:", var.get())

root = tk.Tk()
var = tk.StringVar()
option_menu = ttk.OptionMenu(root, var, "Option 1", "Option 2", "Option 3", command=callback)
option_menu.pack()

root.mainloop()

import tkinter as tk
from tkinter import ttk

def callback():
    if not callback.called:
        callback.called = True
        print("OptionMenu selected:", option_var.get())

root = tk.Tk()
callback.called = False
option_var = tk.StringVar()
option_menu = ttk.OptionMenu(root, option_var, "Option 1", "Option 2", "Option 3", command=callback)
option_menu.pack()

root.mainloop()

import tkinter as tk
from tkinter import ttk

def callback(event):
    print("OptionMenu selected:", option_var.get())

root = tk.Tk()
option_var = tk.StringVar()
option_menu = ttk.OptionMenu(root, option_var, "Option 1", "Option 2", "Option 3")
option_menu.bind("<<ComboboxSelected>>", callback)
option_menu.pack()

root.mainloop()