We all have seen this phenomena on a lot of coins over the years and especially Silver U.S. coinage but it has occasional surface of some Clad coinage as well. I am sorry but it is not doubling and if memory serves me correctly, it is caused by multiple repairs of grinding and polishing of the Die and the Mint Worker trying to be careful and not grind or polish into the images. Due to this, it creates a raised ridge around the image on the Die which shows up as an inset trough (actually an inset line) around part or all of the images.