Once you get to Jedi padawan (which will take months of grinding, no easy way here) you get a second character slot that you can make into anything you like.
It's easier just to buy a second account. You will have to buy the game again as you will need a second serial number, and pay a second monthly fee.
You can run 2 clients on the same computer at the same time, you have to modify a file and set multiple instances to TRUE or something like that. But I don't know what file it is, there were threads on this subject a few months ago, go look for them.