  The similarity of the visible and dark matter abundances indicates that they
may originate via the same mechanism. If both the dark and the visible matter
are charged under a generalized baryon number which remains always conserved,
then the asymmetry of the visible sector may be compensated by an asymmetry in
the dark sector. We show how the separation of baryonic and antibaryonic charge
can originate in the vacuum, via the Affleck-Dine mechanism, due to the
breaking of a symmetry orthogonal to the baryon number. Symmetry restoration in
the current epoch guarantees the individual stability of the two sectors.
