Dual durometer is non sense on a single pour wheel. The Shore A durometer measure (which is measured by pushing a little pin into the surface of the urethane with a scale like this: https://baxlo.com/en/shore-a-durometer) can only output one value: that of all the mixed chemicals making up the final urethane. Of course on a multi pour wheel each band will have its own durometer. Together the bands will act very differently then on a single pour wheel, thats why you see more and more brands getting rid of the A shore measure. It also says only so much: player weight, skating style, profile shape, core, wheel age, exposure to sun / temperature, shelf life and added chemicals all influence performance on different surfaces.