A relation between N=8 gauge theories in three dimensions

We show that three-dimensional N = 8 Sp(N) and SO(2N+1) gauge theories ow to the same strong coupling fixed point. As a consequence, the corresponding orientifold two-planes in type IIA string theory are described at strong coupling and low-energies by the same M theory background. In the large N limit, these assertions are confirmed by studying discrete torsion in the supergravity theory corresponding to membranes on R-8 = Z(2).