We present a study of a collision-less plasma governed by the Vlasov–Poisson system of equations in one space and one velocity dimension; the plasma is subject to initial density perturbations and to both periodic and non-periodic space boundary conditions. For sufficiently large values of the perturbation's amplitude and sufficiently small values of the Landau damping rate, we observe the development of two streets of phase-space holes each consisting of two counter-streaming families of holes. The two streets move in the phase space at different speeds and they may consist of a different number of holes. The fast moving street develops faster when periodic boundary conditions are used, but it appears to be more prominent and robust under non-periodic boundary conditions. In two instances, the distribution function decays within the slow moving street; it remains unaffected within the fast moving street, but it has much smaller values there.