1. 1837 Hill's drawings - w/2 dots
2. 1839 Perring's book published, drawing has his signature. w/2 dots
3. 1840 Vyse's book published by same publisher, James Fraser. Drawing does not have Perring's signature. NO dots.
Someone mentioned that the snail (horned serpent) was not placed according to protocol, too high up, it should be centered.
This pic shows paint in the crevices. I think it's evidence of erasing and redrawing.
My guess is - they didn't want to leave a big empty space below the snail, so they filled it in with 2 dots. I think the pencil lines were made by them and using those they were able to place the dots in a position that would take up some of the void. Dots would be essentially meaningless, less subject to interpretation than using some other glyph which could jeopardize the Suphis name interpretation.
But nothing we've come up with so far explains the paint blotches around Khufu AND the glyphs to the right of it.