The Bradypodion genus has started to get quite a bit of attention recently as far as diversity goes. One thing that has been found is that a couple species exhibit an incredible range of morphological variation based on the particular habitat they inhabit. Bd. pumilum, for instance, exhibits at least three extremely different body types, which anyone would easily assume were completely different species, depending on if they are from the fynbos, renosterveld or more typical habitats. It has also been found that although they seem morphological different, "Bradypodion karrooicum" is molecularly indistinguishable from Bradypodion ventrale. There is a good chance that the variation you saw may simply be the result of habitat driven phenotypic plasticity. I've sent an email to a colleague, however, to get their thoughts as well and will let you know.
Chris