The idea that rodlike molecules possessing an electric dipole moment could exhibit a ferroelectric nematic phase was suggested more than a century ago. However, only recently such a phase has been reported for two quite different liquid crystals: RM734 [4-[(4-nitrophenoxy)carbonyl)]phenyl 2,4-dimethoxybenzoate] and DIO [2.3',4',5'-tetrafluoro[1,1'-biphenyl]-4-yl 2.6-difluoro-4-(5-propyl-1,3-dioxan-2-yl) benzoate]. For RM734 a direct ferroelectric nematic (N_{F}) to classical nematic N transition was reported, whereas for DIO an intermediate phase N_{x} was discovered between the N_{F} and the N phases. Here we present high-resolution calorimetric evidence that an intermediate N_{x} phase also exists in RM734 along a narrow temperature range between the N_{F} and the N phases.