  It is shown that inhomogeneous Szekeres and Stephani universes exist
corresponding to non-dissipative binary mixtures of perfect fluids in local
thermal equilibrium. This result contradicts a recent statement by Z\'arate and
Quevedo (2004 Class. Quantum Grav. {\bf 21} 197, {\it Preprint} gr-qc/0310087),
which affirms that the only Szekeres and Stephani universes compatible with
these fluids are the homogeneous Friedmann-Robertson-Walker models. Thus,
contrarily to their conclusion, their thermodynamic scheme do not gives new
indications of incompatibility between thermodynamics and relativity. Two of
the points that have generated this error are commented.
