The dispersion relation for the six waves generated in the suddenly created two‐resonance lossy Lorentz medium has been derived and analyzed by the use of a Brillouin‐like dispersion diagram. In comparison to the single‐resonance Lorentz medium, another two new waves were excited. The amplitude, power transmission, and reflection coefficients for these new modes have been derived and analyzed for several values of particle density. It was shown that less than 4% of the pump wave power is transformed into the reflected modes.