  The hypothesis of the single state dominance (SSD) in the calculation of the
two-neutrino double beta decay of Mo100 is tested by exact consideration of the
energy denominators of the perturbation theory. Both transitions to the ground
state as well as to the 0+ and 2+ excited states of the final nucleus Ru100 are
considered. We demonstrate, that by experimental investigation of the single
electron energy distribution and the angular correlation of the outgoing
electrons, the SSD hypothesis can be confirmed or ruled out by a precise
two-neutrino double beta decay measurement (e.g. by NEMO III collaboration).
