  We report on the observation of discrete structures in the electron energy
distribution for strong field double ionization of Argon at 394 nm. The
experimental conditions were chosen in order to ensure a non-sequential
ejection of both electrons with an intermediate rescattering step. We have
found discrete ATI (above-threshold ionization) like peaks in the sum energy of
both electrons, as predicted by all quantum mechanical calculations. More
surprisingly however is the observation of two ATI combs in the energy
distribution of the individual electrons.
