We analyse the properties of a Cournot-Nash equilibrium which arises when two monopolies, operating each in a separate market, become a duopoly in a common market with two sub-markets (the formerly separated markets) and are allowed to price discriminate across submarkets. This equilibrium implies "intra-industry" trade (or "cross-hauling") of identical commodities and freight absorption (which is an increasing function of the slope of the marginal cost schedule). It also leads to price differences such as those observed in the European car market.