We study the equilibrium Gibbs states for a Boson gas model, defined by Bru and
Zagrebnov, which has two phase transitions of the Bose condensation type. The two phase
transitions correspond to two distinct mechanisms by which these condensations can occur.
The first (non-conventional) Bose condensation is mediated by a zero-mode interaction term
in the Hamiltonian. The second is a transition due to saturation quite similar to the
conventional Bose-Einstein (BE) condensation in the ideal Bose gas. Due to repulsive
interaction in non-zero modes the model manifests a generalized type III, i.e.,
non-extensive BE condensation. Our main result is that, as in the ideal Bose gas, the
conventional condensation is accompanied by a loss of strong equivalence of the canonical
and grand canonical ensembles whereas the non-conventional one, due to the interaction,
does not break the equivalence of ensembles. It is also interesting to note that the type
of (generalized) condensate, I, II, or III (in the terminology of van den Berg, Lewis and
Pule), has no effect on the equivalence of ensembles. These results are proved by computing
the generating functional of the cyclic representation of the Canonical Commutation
Relation (CCR) for the corresponding equilibrium Gibbs states.