From Pluralpedia, the collaborative plurality dictionary
duality (v.)
Applies toheadmates, system functions

Duality is a sort of double, with the only exception for it being that it's not a separate headmate (but can become one), it's the consciousness of one headmate, in two somas- where one can be busy (when needed to be fronting, but cant coz they're busy), and the other who is free (and able to front).

Duality is useful for when the headmate [that's projecting] needs to be doing something but can't.

Memory sharing may or may not be accessible.

The events happening to the projector may or not be relevant to the projection.

Extensive usage of this method may result in a new headmate.