So does the US, they even occasional win elections, even to Congress (historically, there is at least one case where one displaced a major national party in the state-level duopoly), that doesn't mean FPTP doesn't tend toward duopoly. (FPTP plus a strong Presidential system tends more strongly toward duopoly; FPTP plus a strong Presidential system plus an indirectly-elected President where Presidential electors are mostly elected by multimember FPTP tends even more strongly to duopoly.)