  Reciprocal pairs of quantum channels are defined as completely positive
transformations which admit a rigid, distance-preserving, yet not
completely-positive transformation that allows to reproduce the outcome of one
from the corresponding outcome of the other. From a classical perspective these
transmission lines should exhibit the same communication efficiency. This is no
longer the case in the quantum setting: explicit asymmetric behaviours are
reported studying the classical communication capacities of reciprocal pairs of
depolarizing and Weyl-covariant channels.
