I am not aware that either Subpart G, Appendix 3, Appendix 6 or Appendix 7 to Part-FCL make any differentiation between an SP or MP instrument rating. I therefore consider a licence entry e.g IR(MPH) to be tautologous as it is the type rating that determines the requirement for SP or MP.
I guess to a limited extent, it is up to the NAA to determine what is entered onto a licence.