我的带有聊天过滤器事件的discord.py机器人发送2条或更多消息，而不是1条

import discord
from discord.ext import commands

bot = commands.Bot(command_prefix='!')

@bot.event
async def on_ready():
    print(f'Logged in as {bot.user}')

@bot.event
async def on_message(message):
    if message.author == bot.user:
        return
    await message.channel.send('Hello, world!')
    await bot.process_commands(message)

bot.run('YOUR_BOT_TOKEN')

@bot.event
async def on_message(message):
    if message.author == bot.user:
        return
    await message.channel.send('Hello, world!')
    await bot.process_commands(message)

import logging

logging.basicConfig(level=logging.DEBUG)

@bot.event
async def on_message(message):
    logging.debug(f'Message received from {message.author}: {message.content}')
    if message.author == bot.user:
        return
    await message.channel.send('Hello, world!')
    await bot.process_commands(message)