Area of the cumulative stellar distribution within 0.5R_h (ϕ(<0.5R_h)) for the two populations in models: (a) N2M and (b) N05M. As in Fig. 3, we centre the time evolution at the respective time of the first core collapse. The two populations in model N2M have not achieved complete spatial mixing and ϕ_2P(R < 0.5R_h) > ϕ_1P(R < 0.5R_h). The model N05M has already attained a significant spatial mixing and ϕ_2P(R < 0.5R_h) ~ ϕ_1P(R < 0.5R_h). Furthermore, for model N05M, both populations show the same rate of increased concentration at core collapse, which explains the lack of signatures in S²(E) (see Fig. 3).