it seems they fixed it so you can't have more than 1 acc logged into a lobby, so you can't quickly login to the same world anymore.
is there any other methods out there?

 

Not the appropriate section. Ask a mod to move it if you're still after an answer. This type of question belongs here:
http://www.sythe.org/runescape-3-general/
or
http://www.sythe.org/runescape-2007-general/

 

I can get multiple accounts into the lobby, the same as always. Logging in quickly with 2 or more accounts into the same world is working fine for me too.

When you try to enter the lobby with a second account, what exactly does it say?

 

search random.dat file in your jagex cache.

Mark it as read-only.

 

Use a Virtual Machine such as VMPlayer.