  The Lambda(1405) resonance is studied by a chiral unitary approach, in which
the resonance is dynamically generated in coupled-channel meson-baryon
scattering. Investigating the analytic structure of the scattering amplitudes
obtained by the chiral unitary approach, we find two poles around the energies
of the Lambda(1405) coupling differently to the meson-baryon states. We reach
the conclusion that the Lambda(1405) resonance seen in experiments is not just
one single resonance, but a superposition of these two states.
