Last slash command registered is duplicated with no `id` in `bot._application_commands`

[krittick]

Summary

When multiple slash commands are registered, the last one is registered again but without an id in bot._application_commands. It's likely that this will have cascading effects elsewhere, but so far was only noticed during testing for #838.

Reproduction Steps

Register more than one slash command and retrieve bot._application_commands

Minimal Reproducible Code

from discord.ext import commands
import discord
intents = discord.Intents.all()


bot = commands.Bot(command_prefix=[">"], intents=intents, owner_ids=[...])


@bot.slash_command(name="id_test", guild_ids=[...])
async def id_test(ctx):
    await ctx.respond("Test for id issue")
    await ctx.respond(bot._application_commands)


@bot.slash_command(name="id_test2", guild_ids=[...])
async def id_test2(ctx):
    await ctx.respond("Test 2 for id issue")
    await ctx.respond(bot._application_commands)

bot.run("token here")

Expected Results

Slash commands should not be added again with an empty ID once registered.

Actual Results

The following shows for _application_commands: (issue in bold)

{None: <discord.commands.SlashCommand name=id_test2>, '936482856040017940': <discord.commands.SlashCommand name=id_test>, '936482973384073356': <discord.commands.SlashCommand name=id_test2>}

Intents

All

System Information

- Python v3.10.0-final
- py-cord v2.0.0-beta
    - py-cord pkg_resources: v2.0.0b4872+g16661e72
- aiohttp v3.8.1
- system info: Windows 10 10.0.19043

Checklist

• I have searched the open issues for duplicates.
• I have shown the entire traceback, if possible.
• I have removed my token from display, if visible.

Additional Context

This might get fixed with #759 but I'm logging the issue to keep it on our radar to test with those changes either way.

[BobDotCom]

I did run into this issue when writing #759 but I'm pretty sure it does fix it, so I'll link that PR here.