I've managed to get my hands on some boots that are extremely similar to the DREDD boots.
I believe they could in-fact be the base boot, or more likely be the basis of the pattern for the production made boots. I think the similarities are too close for them to not have any link. Here is a photo for comparison:
It's entirely possible that a pattern was made from this style of boot and the screen used boots constructed from that pattern. Which would explain the different textures in leather and different sole type.