112-75 RP

i have a MM 112-75 RP amp dual channel with a ceramic speaker in nearly perfect condition is it rare

Your amp is not particularly rare as far as guitar amps in general go (meaning they are not collectible in the same sense as an old Fender or Marshall might be).
However, they are great amps that are constructed better than most amps made in the last 2 decades so they are highly valued by those who know!