Grinsell reported others, but I have not been able to trace any illustration of them.
On re-reading the second quotation, the context certainly suggests that Osburn was talking about the name as a quarry mark. What he does not make clear is who is supposed to have observed it or reported it. Surely Lepsius and crew would have spotted it, when they were there?
On balance it seems most likely that Osburn is just confused, as we might infer also from his muddled chronology.