biplicity

The state of being twice folded; reduplication.

[…]that certain characteristic properties of the bacterial flagellum can be imitated in a wire coil model. These properties are: (1) the arc which is visible frequently at the end of a flagellum (Figs. 10 and 11), and (2) the phenomenon of “biplicity,” that is, the sudden appearance of one-half the usual pitch (Fig. 12).

Doubleness, the state of being double.

The integration and differentiation of vital function on the one hand, and the preparation and composition of food-material on the other hand form — as we will become fully aware further on — the two great divisions in the subject-matter of the science of organization, divisions corresponding to the fundamental biplicity of all advanced organization, its animal and its vegetative life.

He who reads them will see that Mr. Darwin by no means minces matters with Lyell[…] There may be a certain biplicity of kindness and courtesy in Mr. Darwin ; but there is no duplicity of his essential manhood and truth.