The AA'$3$Mn$_4$O${12}$ family of manganites with quadruple perovskite structure has recently attracted a lot of interest as a disorder-free model system for many of the phenomena usually sought after in doped manganites, such as charge, orbital and spin ordering phenomena and multiferroicity. Within this family of metastable compounds, PrMn$7$O${12}$ is the only known phase to crystallizes in two different forms with rhombohedral and monoclinic symmetry depending on the synthesis conditions. Although the two forms differ slightly from the crystallographic point of view, their magnetic behavior as observed from bulk magnetization is dramatically different. A detailed investigation of the magnetic structure by means of high-resolution powder neutron diffraction is therefore needed in order to characterize the ground state of these intriguing phases.