I don't think so – France uses this exact model, and their party system has just in the last 15 years or so transitioned out both of the former top two parties (PS and LR).
If anything, I would expect this model to reduce duopoly. An unpopular republican might be overtaken by a candidate from the libertarians in the first round, giving them a shot at victory which they could hardly get if the ghost of "wasted votes" on third-parties was haunting them.
If anything, I would expect this model to reduce duopoly. An unpopular republican might be overtaken by a candidate from the libertarians in the first round, giving them a shot at victory which they could hardly get if the ghost of "wasted votes" on third-parties was haunting them.