Double vs bilateral descent 1-2 no inheritance, no ancestor, temporary

Murdock 1962, American anthropologist. In his paper, Double descent mentions examples like to todas of India, ashanthi of Africa, Bantu of Africa. 

Ember and ember book. Society where there is commercialization, and increasing role of state importance of kinship declines and creates by little kinship. For example Chipewyan of sub Arctic Canada.

Why double doesn't exist. Ask sir ?