It is believed that slugs have four noses, although they don't have the same type of respiratory system that a human being has so their nose performs a different function to ours.

If by noses you mean a nose like humans have to breathe through , they have none. But they do have appendages (4) that can sense heat and other stimuli, in other words they have 4 sensory organs where there "nose" looks like it should be. But no actual nose.