I think it is said that Gauss had ten different proofs for the law of quadratic reciprocity. Any good theorem should have several proofs, the more the better. For two reasons: usually, different proofs have different strengths and weaknesses, and they generalize in different directions - they are not just repetitions of each other.

24th of May, 2004 prior to the Abel prize celebrations, Interview with Michael Atiyah and Isadore Singer