  We show that the vanishing of the one-loop beta-functional of the doubled
formalism (which describes string theory on a torus fibration in which the
fibres are doubled) is the same as the equation of motion of the recently
proposed generalised metric formulation of double field theory restricted to
this background: both are the vanishing of a generalised Ricci tensor. That
this tensor arises in both backgrounds indicates the importance of a new
doubled differential geometry for understanding both constructions.
