Variations of perovskite superstructure type and magnetic properties across the high pressure CaxMn2-xFeReO6 series have been investigated by powder neutron diffraction, x-ray magnetic circular dichroism, and magnetisation measurements. Monoclinic P21/n A2BB´O6 double perovskite solid solutions with rocksalt type ordering of B/B’-Fe/Re cations but no A-cation order are discovered to exist only close to the end members 0 < x < 0.17 and 1.73 < x < 2. Compositions in the range 0.74 < x <~1.1 adopt a tetragonal P42/n AA’BB´O6 double double perovskite phase based on CaMnFeReO6, which has both columnar A/A’-Ca/Mn and rocksalt B/B’-Fe/Re cation orders. Two-phase coexistence of double and double double perovskites occurs over wide regions between these limits. All samples are ferrimagnetic with Curie temperatures near 500 K. Low temperature Mn spin order is also observed in the Mn-rich double perovskites and the double double perovskites. Spin reorientation transitions observed across all of the double perovskites are shown to result from 5d2 Re5+ orbital ordering, but this does not occur in the double double perovskites. The Ca-rich double perovskites show significant magnetic coercivity at low temperatures.