Man pages matching name mpi_lookup_name in section 3:

MPI_Lookup_name.3.en	debian 10 / lam4-dev
MPI_Lookup_name.3.en	debian 10 / mpich-doc
MPI_Lookup_name.3.en	debian 11 / lam4-dev
MPI_Lookup_name.3.en	debian 12 / lam4-dev
MPI_Lookup_name.3.en	debian 12 / mpich-doc