Eq1 Fixed is dubious

I added this instance without not too much thinking:

instance Eq1 Fixed where
    liftEq _eq (MkFixed x) (MkFixed y) = x == y

but I'm not sure it makes sense as liftEq allows comparing of different types, which is very not right for Fixed types:

Prelude Data.Fixed Data.Functor.Classes> liftEq undefined (12 :: Micro) (12000 :: Milli) 
True

One would expect 12000 :: Micro and 12 :: Milli (i.e. otherway around) be equal! (or alternatively the first argument of undefined would make some resolution conversion)