I've been wanting to know if you can connect to LAN worlds with the same IP address as you. My brother wants to get another minecraft account so we can play together on the same world but we both have the same IP address. Is it possible to connect to the same LAN world if we both have the same IP address?
You'll be able to play just fine!
You are probably looking at your external IP address, which is actually the IP address that your router uses to connect you to Internet at large. That's shared by all the computers on your home network, but only for the purpose of accessing the Internet and that IP address has nothing to do with playing LAN games.
On your home network (probably wifi, right?) you have a completely separate collection of IP addresses just for your computers' local networking use, and each computer gets an unique address from that collection. (Your router tries very hard to makes sure one computer never has the same IP address as another computer. It's possible, but close to impossible to happen unless someone has been seriously messing with the router's configuration.)
So, you have different addresses, which makes everything fine. As a bonus, you don't even need to care about IP addresses to play Minecraft over LAN, because it will autodetect worlds that have been opened to LAN and just let you click-and-play.
It turns out, no, a separate IP address is not required. As is the norm with my answers, I can back this up with some SCIENCE.
I opened up two instances of Minecraft. On the first, I opened up a world to LAN. On the second, I opened up the multiplayer menu. And to my surprise and delight, it showed up! However, when I tried to log in, it gave me this message:
So no, you do not need two separate IP addresses, or even two separate computers. You just need to be connected to the same local network, and also have two separate Minecraft accounts.
My two daughters are playing Minecraft, they want to play on the same world, but they can't as the server they are trying to play on only allows one player per IP. As the world will only ever see the external IP given to us from the provider, they as result cannot play on the same world.
The only way to do that would be to somehow trick the world into seeing one of their computers with another IP. I haven't tried it yet, but maybe some sort of proxy setting.