For such ancient paintings, often repair work has been done, sometimes over considerable portions of the surface. It's entirely possible that Joseph's face had

For such ancient paintings, often repair work has been done, sometimes over considerable portions of the surface. It's entirely possible that Joseph's face had to be redone (water damage, smoke, a tear) a century later and of course was done by a different painter. I'd expect most old paintings would 'suffer' from this. Not unlikely some of the training data (49 paintings 'by Raphael') suffered from this, muddying the conclusion further.