We show that three-dimensional N=8 Sp(N) and SO(2N+1) gauge theories flow
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 R8/Z2.Comment: 8 pages, harvmac; an acknowledgement adde