Let $W$ be a finite dimensional purely odd supervector space over $mathbb{C}$, and let $sRep(W)$ be the finite symmetric tensor category of finite dimensional superrepresentations of the finite supergroup $W$. We show that the set of equivalence classes of finite non-degenerate braided tensor categories $C$ containing $sRep(W)$ as a Lagrangian subcategory is a torsor over the cyclic group $mathbb{Z}/16mathbb{Z}$. In particular, we obtain that there are $8$ non-equivalent such braided tensor categories $C$ which are integral and $8$ which are non-integral.