I understand your point, and to that effect I'd opt for a duopoly over a monopoly ten times out of ten. That said, even duopoly for internet options sucks. Here in Canada your choice between Bell/Rogers, or Bell/Vidéotron, or Bell/Shaw, etc. makes almost no difference vs the choice between a single one of them. They just bought out almost all independant providers in the country (we're all enjoying huge discounts right now that are obviously temporary, and were used as a tool to undercut them to make the purchases pass more easily).

I would argue it's more important to have more than one option, but it still DOES matter who those options are.