Yes, that is how those models get a black outline, basically the larger inside out model is textured black, when looking at the outside faces gameguru will render them see through so you can see the inner faces on the other side, because its slightly bigger than the real model you would only see the edge of the black model, making it look like the main model has a black outline.
Primary Desktop:
i7 7700,k NV1070 8GB, 16GB 3200mhz memory, 1x 2TB Hybrid, Win10.
Secondary Desktop:
i5 4760k, NV960 2GB, 16GB 2333mhz memory, 1x 2TB Hybrid, Win10.
Laptop:
i3, Intel 4000 series graphics, 6GB memory, 1x 500gb HDD, Win8.1.