The design of this paper is to consolidate a comprehensive model pertaining to the evolution of Egyptian calendars over three millennia of Pharaonic history, as an extension of this writer's earlier work on calendars. This model is a variation on the model advanced by Ludwig Borchardt and Richard Parker. While hardly immune from criticism, the Borchardt-Parker model has been prevalent in the second half of the twentieth century. According to this model, there were three calendars in ancient Egypt, two lunar and one non-lunar called civil. According to the variant model, there are only two calendars at any one time, the dominant civil calendar and a marginal lunar calendar of religious purport and of incomplete articulation. After the creation of the two calendars in prehistory and early history, only one truly significant event took place in all of Egyptian calendar history, around the fourteenth century B.C.E. Before the event, the lunar year began around the rising of Sirius in July. After the event, it began around the first new moon following civil New Year's Day. Owing to the backward wandering of the civil year, civil new year came to coincide with the rising of Sirius in the later fourteenth century B.C.E. The lunar calendar was unhooked from the rising, as it were, and attached and subordinated to the civil calendar. A double calendar, spiraling forward in time like a double helix, was the result. If the earlier and later beginnings of the lunar year are counted as two different calendars, there were three calendars, one civil and two lunar. However, it seems preferable to count just one lunar calendar, one that changed in regard to just one feature, its year's beginning.