Effect of the capture into the 3:4 and 2:3 mean motion resonance for a pair of co-orbital planets m₁ and m₂ initially in a horseshoe configuration. The co-orbitals start with an amplitude of libration of ζ_max − ζ_min = 320°. The colour code represents the amplitude at the end of the simulation. In most cases, the capture in MMR with another planet tends to greatly reduce the amplitude of libration of the co-orbitals’ resonant angle. White pixels represent the systems for which the co-orbitals were not in the intended resonance with m₃ at the end of the simulation. See the text for more details.