Equivalence of Two-Loop Superstring Amplitudes in the Pure Spinor and Ramond-Neveu-Schwarz Formalisms

The pure spinor formalism for the superstring has recently been used to compute massless four-point two-loop amplitudes in a manifestly super-Poincaré covariant manner. In this Letter, we show that when all four external states are Neveu-Schwarz states, the two-loop amplitude coincides with the Ramond-Neveu-Schwarz result.