ok here goes d00d, but you really should search the forums before you post wildly, because this has been discussed many, many times before -
to get the double bladed lightsabre, start a multiplayer game as a server, and, when in the game, bring down the console and type "devmap <map>" without the quotes, where <map> is the name of a map in the game - two good ones are "bespin_ffa" and "pit".
Once in the new map cheats will be enabled. Bring down the console and type "\THEDESTROYER" or "/THEDESTROYER" (can't remember which, i got bored of this cheat quite quickly). your saber should be off when you type this, and when you press enter, the screen will shake and the saber will be double bladed.
NB All the animations are the same, but the second blade will do damage to others, but not to you, which is lucky because the second blade passes through you all the time.
Hope that helps, and, in future, PLEASE search forums before you post, a lot of stuff will have been discussed before.