I think it was Pelling who first suggested that glyphs had been modified throughout the book, although whether by the original scribes or others is impossible to say.
Stolfi also did quite a bit of work on this, and also has suggested that many of the illustrations were painted in by a later artist, possibly unconnected with the original scribes.
What we don't see are the standard manuscript practices of crossing out and amendements. Instead, some glyphs appear to be changed.
His theory, IIRC, was that the text was first written onto wax tablets and then copied onto the manuscript.
Stolfi also did quite a bit of work on this, and also has suggested that many of the illustrations were painted in by a later artist, possibly unconnected with the original scribes.
What we don't see are the standard manuscript practices of crossing out and amendements. Instead, some glyphs appear to be changed.
His theory, IIRC, was that the text was first written onto wax tablets and then copied onto the manuscript.