如何再使用一次相同的mp3文件？

import tkinter as tk 
from tkinter import filedialog
from pygame import mixer

mixer.init()

firsttime = False
song2switch = True

root = tk.Tk()
 
canvas = tk.Canvas(root, width=400, height=250)
canvas.pack()

def loadsong1():
    global song1
    song1 = tk.filedialog.askopenfile(parent=root, initialdir="C:/",title="choose first song",filetypes=[("mp3 files", ".mp3")])
def loadsong2():
    global song2
    song2 = tk.filedialog.askopenfile(parent=root, initialdir="C:/",title="choose second song",filetypes=[("mp3 files", ".mp3")])
def play():
    mixer.music.load(song1)
    mixer.music.play()
def switch():
    global firsttime
    global song2switch
    global time_of_song
    if firsttime == False:
        time_of_song = mixer.music.get_pos()
        time_of_song /= 1000
        mixer.music.stop()
        mixer.music.load(song2)
        mixer.music.play(start = time_of_song)
        firsttime = True
        song2switch = False
    else:
        if song2switch == False:
            time_of_song = mixer.music.get_pos()
            time_of_song /= 1000
            mixer.music.stop()
            mixer.music.load(song1)
            mixer.music.play(start = time_of_song)
            song2switch = True

playbutton = tk.Button(canvas,text="PLAY",command=play)
canvas.create_window(200,240,window=playbutton)
load1button = tk.Button(canvas, text="Load Song One",command=loadsong1)
canvas.create_window(100,240,window=load1button)
load2button = tk.Button(canvas, text="Load Song Two", command=loadsong2)
canvas.create_window(300,240,window=load2button)
switchbutton = tk.Button(canvas, text="SWITCH", command=switch)
canvas.create_window(200,200, window=switchbutton)

root.mainloop()

我正在尝试使这种音乐播放器可以在两首歌曲之间切换，同时保持彼此相同的时间（例如，当我切换已经播放一分钟的歌曲时，另一首将开始播放一分钟），但是当我尝试将其切换到第一首歌曲时，会出现此错误：

pygame.error：无法读取音频数据的前12个字节

我该如何解决？