  The groups $O(N)$ and $Sp(N)$ are related by an analytic continuation to
negative values of $N$, $O(-N)\simeq Sp(N)$. This duality has been studied for
vector models, $SO(N)$ and $Sp(N)$ gauge theories, as well as some random
matrix ensembles. We extend this duality to real random tensor models of
arbitrary order $D$ with no symmetry under permutation of the indices and with
quartic interactions. The $N$ to $-N$ duality is shown to hold graph by graph
to all orders in perturbation theory for the partition function, the free
energy and the connected two point function.
