I had a clutch of carpet python eggs which looked similar, but more extreme. The uncalcified patched looked like polka dots all over the eggs (thirty something of them). They were yellow at first, I thought the clutch was no good, but incubated them anyway. They gradually turned black, which I thought was the yellow egg yolk going off, but it turned out that the black colour was the baby snakes inside, the 'polka dots' were like windows, you could see into the eggs. All the eggs were fertile and there were three sets of twins. One set of twins hatched out fine, one set had one hatch and one die in the egg, the last set of twins died inside the egg, the rest of the eggs hatched into healthy babies. The twins which did hatch were among the best feeders and grew very well.