  We show the existence of a self-similar solution for a We prove the
uniqueness of the self-similar profile solution for a modified Boltzmann
equation describing probabilistic ballistic annihilation. Such a model
describes a system of hard spheres such that, whenever two particles meet, they
either annihilate with probability $\alpha \in (0,1)$ or they undergo an
elastic collision with probability $1-\alpha$. The existence of a self-similar
profile for $\alpha$ smaller than an explicit threshold value
$\underline{\alpha}_1$ has been obtained in our previous contribution (J.
Differential Equations, 254, 3023--3080, 2013). . We complement here our
analysis of such a model by showing that, for some $\alpha^{\sharp} $ explicit,
the self-similar profile is unique for $\alpha \in (0,\alpha^{\sharp})$.
