What the Professors Foglio have done with Girl Genius is very likely unique. They first made a graphic version of the story and then produced a prose version of the story. Usually, this process is reversed with one author producing a prose version of a story and then someone else later uses the prose work to produce a comic book or a cinema or both. Usually, any differences between the prose version of a story can be construed as just another version with minor or major deviations from the original. The reason for this is that the author of the prose version of a yarn has never been known to produce a graphic version or the reverse. This is a unique situation and it remains to be seen if the differences are accidental oversights, or are purposeful deviations along another timeline.