Does it matter, except on an OCD semi academic level? I don't think I've ever come across an enlarging lens that is not coated at all, even the early Kodak Ektars from the 1940's are coated.
I haven't tried to look up any documentation but am certain that when Rodenstock introduced the APO-RODAGON-N line (IIRC in the mid 1990's) one of the differences was that the lenses were multicoated whilst in the previous APO-RODAGON line the lenses were not (ie. they were single coated). I don't know if multi coating was later applied to all Rodenstock ELs.