i have another method to dual login.
1. Create a user account in your computer, a login account.
(if you have already another account in your computer, there's no need to.)
2. login into cabal normally. and login your account.
3. go to cabal directory and right click "cabalmain.exe"
4. click "run as...."
5. select the second option and login your other account (not the current one).
6. click OK.
7. cabal update screen will open. Click START CABAL.
8. login your other account.......
9. you are already dual logging.
BUT it auto closes your character back to the login screen after a few seconds. an error will occur that will make it disconnected.
IN SHORT, this method is only good if you want to trade an item to the other character. So, place your first logged in character in the same place where your second char is located. when your second char is logged in, immediately Trade. for about 15 seconds your second char will be disconnected.
I know this is pretty lame but i do it when i need to trade with my other char.