Sir James Schaw of Sauchie - Extra generation?

David Marshall's 'Genealogical notes anent some ancient Scottish families" https://archive.org/details/anent1884/page/119/mode/1up
adds an extra generation here between Sir James Schaw, Kt. and Sir James Schaw of Sauchie
So, Sir James Shaw x Isobell is the son of a Sir James Shaw of Sauchie, who is the son of Sir James Shaw m. Mary de Annand.

1.Sir James Schaw, Kt. x c 1431 Mary de Annand.

2.Sir James Shaw of Sauchie

3. Sir James Schaw of Sauchie x c1483 Isobell

I don't know if it matters / makes a difference to dates?