WARSAW, Poland – Two parties – one pro-business, the other anti-corruption – were favored to oust Poland's ruling ex-communists in a general election Sunday that could determine how quickly the U.S. ally adopts the euro. Also, two brothers – identical twins – are competing on the political stage, one leading the Law and Justice party poised for a good result Sunday, the other a leading candidate in presidential elections Oct. 9. When Poland entered the European Union last year as the bloc's largest country, it agreed eventually to replace the zloty with the EU common currency. To do that, it...