> how does the presence of many similar human-like figures without those two dots match the same phenomenon

Toroidal instability and shape-evolution is given considerable attention in the paper. The toroids fold and warp and what the human eye perceives will depend on the viewing angle. If you're looking at the toroid edge-on you get the "dot" effect, cf. Figure 31 in the first paper. The "double-dot" squatter petroglyphs are rarer, as that paper points out.