Actually that was my favorite part that he did. Because it was never supposed to sound like the original to begin with; just the fact that he had said those words before was the symbolism of that moment. The moments that speech is given are rather different as well; in KH1 it's an epic speech to Sora, with Ansem SoD mocking Riku and his fall, whereas in BBS, it's a quiet moment of reflection and self-satisfaction upon accomplishing the goal of taking over Terra's body.