The aim of this work is to understand the origin of the difference in the behaviour between the two doped manganites Sr0.65Pr0.35MnO3 and Sr0.70Ce0.30MnO3. The hypothesis we wish to explore is that the availability of Ce4+ in Sr0.70Ce0.30MnO3 promotes additional disorder in the system and thus suppresses the formation of long range antiferromagantic coupling. This additional disorder also drives a remarkable difference in the high temperature behaviour, resulting in the loss of long range orbital ordering