The paper presents the theoretical simulation results of mmWave frequency modulated continuous wave (FMCW) radars in multi-target mode. The speed of objects is determined by a segment of constant frequency, and the ranges are determined twice - by the first and second chirps of long duration, but with different deviations and frequency rise steepness. The method consists in the fact that the proposed functional with the correct speed-range pair has a minimum, which allows you to select the correct speed-range pair from the sets of speeds and ranges of all targets. The dependence of probability of multiple targets speed and range correct determination in the multi-target mode on the range of the FMCW radar has been investigated. The results can be used by developers to design optimized radars.