  The equilibrium properties of a Janus fluid made of two-face particles
confined to a one-dimensional channel are revisited. The exact Gibbs free
energy for a finite number of particles $N$ is exactly derived for both
quenched and annealed realizations. It is proved that the results for both
classes of systems tend in the thermodynamic limit ($N\to\infty$) to a common
expression recently derived (Maestre M A G and Santos A 2020 J Stat Mech
063217). The theoretical finite-size results are particularized to the
Kern--Frenkel model and confirmed by Monte Carlo simulations for quenched and
(both biased and unbiased) annealed systems.
