Is it possible to do this offline? I've tried changing the char.png file, and it changes my image, but it also changes both of theirs and we all still look the same, and they can't see it.
When you say "play offline", do you mean you simply play the solo game mode? Or do you mean that you play without a net connection.
If you're playing without a connection to the internet, you won't be able to log in to your Minecraft account. Even if you've changed the skin associated with your account, when playing offline your skin will always be the default.
I think an offline name change is preferable to an offline skin change.
If the server you are running is
As an aside, offline mode can be achieved easily if you use MC Patcher - an awesome way to load mods and easy way to get your minecraft.jar all set up without opening and closing it manually. When you get it set and 'Patch' it, you can click
Anyways this method would seem likely to work on multiple machines (most likely LAN only) but try to get that name change, work it to an account registered and change the char.png. Hopefully this will work out, maybe would be good to not log into the second minecraft.exe with a verified account to avoid having it share the same skin.
Ways to get the name changed
Information found from here: How do I change player name in minecraft multiplayer in offline mode in Linux?
Copy + Paste to new applescript, compile, save as application, launch:
The skin is linked to the account, so, no, you can't have multiple skins on the same account.
I didn't even know you could login with the same account more than once at a time.