Your ignorance astounds me.
If you actually read [if you're capable of doing so, which I doubt] anything about the games, you'd know that they were totally different. Digimon World DS is, funnily enough, modelled on the fairly popular, Digimon World game for the Playstation which was released in 2000. Are they copying a game released six years after the concepts birth?
Are Digimon games not allowed to be on the DS platform? Because that's all that the two games have in common. Would you rather that Pokemon games were the only games to be published, on any platform? That's called a monopoly, and it's illegal you moron.
You're a fucking retard, get off of the forums.