Just because he is seen absorbing a blue materia doesn't mean that is the only one he used. I'm sure he had a red one in his arm too, we just didn't see him put it in. What is so outrageous about that? We don't need to see everything that goes on behind the scenes.

Actually Griff, Cloud was the only successful Sephiroth "Clone". Since he was the only one to make it to the Reunion in the game.