  We study dynamics of populations of resonantly coupled oscillators having
different frequencies. Starting from the coupled van der Pol equations we
derive the Kuramoto-type phase model for the situation, where the natural
frequencies of two interacting subpopulations are in relation 2:1. Depending on
the parameter of coupling, ensembles can demonstrate fully synchronous
clusters, partial synchrony (only one subpopulation synchronizes), or
asynchrony in both subpopulations. Theoretical description of the dynamics
based on the Watanabe-Strogatz approach is developed.
