[en] Partial substitution of manganese by cobalt in rare-earth perovskites REMnO₃ leads to unusual magnetic phenomena because of the simultaneous presence of Mn³⁺, Mn⁴⁺, Co²⁺ and Co³⁺ species. The magnetic nature of the RE cation plays a fundamental role in the magnetic properties. We present herein two specific families: for RE=La the magnetic behavior of the |Co+Mn| network is observed, while for Gd its strong magnetic moment interacts with the transition metals, leading to a spin reversal state. Magnetic interactions are maximized at x=0.50, as if two regimes exist: for x<0.5 Co substitutes Mn in the REMnO₃ manganite, and for x>0.5 Mn substitutes Co in the RECoO₃ cobaltite