Studies of the magnetization curves of electron-doped single-crystal manganites Ca1 - x Ln (x) MnO3 (Ln = La3+, Ce4+; x a parts per thousand currency sign 0.12) in strong pulsed magnetic fields of up to 350 kOe have revealed a metamagnetic transition in Ca0.9Ce0.1MnO3 in the temperature range 77-190 K. The critical transition fields increase to similar to 350 kOe with the temperature decreasing to 100 K. The spin polarization is similar to 50% of the theoretical value. These results are interpreted as due to "melting" of the orbital/charge ordering below the temperature T (OO/CO) = 185 K = T (N) (of the C type AFM phase); this entails a decrease in the volume of the ordered phase with localized carriers and an increase in the volume of the ferromagnetic phase with delocalized carriers. The temperature and field dependences of the magnetization are used to compare two manganite systems in the region of the two-phase magnetic state.