Don't bother going out of your way to kill Django Williams, the corp with just fett him up again. I've personally seen him killed twice and done him in once myself.
In the Cosmic Era there is a certain demi-immortality that exists. By copying a person's mind and creating a Persona Engram and using force grown cloned bodies, it is possible to produce an endless series of copies of the same person. In the shadows of the Megacorps and New Earth Governments this is more common than might be expected. A small number of well trained men can be sent on missions, even suicide missions and three months later a new batch is ready to roll.
In Unconditioned Fetting, the clone is not aware that they are a clone. They do not have memories of the cloning center, or the time spent growing in a tube. Unconditioned clones tend to be more capable and competent, but run the risk of becoming loose cannons if they discover their artificial nature. A good example of an unconditioned fetting would be James Bond. He keeps coming back again and again, and how does he survive some of those situations he ends up in? The answer is he doesn't.
Conditioned Fetting is the cloning process where the clone knows they are a clone, they know they are expendable, a sort of middle point in a production run and their value is not based on their human rights or individuality but on their ability to perform. The conditioning is based around keeping the 'unit' loyal and functional. Examples of Conditioned Fetting would be the clones from The Sixth Day, or Rei from Neon Genesis Evangelion
The origin of the term Fetting goes back to Boba Fett, a minor background character in the original Star Wars trilogy who had a few scenes and a few lines and was later 'killed' after being devoured by a giant desert vagina dentata. The popularity of the character ensured that no matter what happened, Fett would just keep coming back again and again. Originally this was attested to his badass armor and Mandalorian iron will. In the Prequel Trilogy we find the armor isn't all that awesome, and that Fett is an unconditioned clone of his father. So, it's actually a series of Jango Fett clones rather than just one supremely badass individual.