This paper studies the incentives for multiproduct duopolists to sell their products as a bundle. It is shown that contrary to the monopoly case bundling may reduce profits and increase consumer rent. This is the case if consumers' reservation values are negatively correlated. The reason is that bundling reduces consumer heterogeneity and makes price competition more aggressive. This effect can dominate the sorting effect that is well known for the monopoly case. Firms are in a prisoner's dilemma situation because they would be better off without bundling. Despite the lower prices a welfare loss occurs because some consumers do not buy their prefered product which results in distributive inefficiency. If firms can influence the correlation by choosing their location in the product range they try to avoid negative correlation and choose minimal differentiation in one good.