While “The Expendables 2″ claimed its second overseas weekend victory with $20.1 million, China dominated B.O. headlines as “The Amazing Spider-Man” and “The Dark Knight Rises” went head-to-head there, nabbing $5.5 million and $4.5 million, respectively, on the first day of their Aug. 27 bows.China Film Group, as it had before with big Hollywood movies, had pitted the superheros against each other, hoping to limit their box office. Moreover, the tentpoles in China continued to rule locally during second-day outings: “Spider-Man” earned $5.3 million, bringing the pic’s worldwide cume past $710 million, while “Dark Knight” increased by 2%, with $4.6 million. The Batman finale so far has tallied nearly $960 million globally. Fox’s “Prometheus,” however, further clutters the Chinese B.O., bowing there Sept. 2. But “Dark Knight” — because of its Chinese bow and an Aug. 29 launch in Italy — could again reclaim international weekend bragging rights in its seventh frame. The film earned $16 million last weekend — down 25% — from 62 holdover markets. “The Expendables,” meanwhile, benefited from expansions into France, where the film outpaced its predecessor by 25%, with $5 million, and Spain, which contributed $2.5 million — 40% better than the first. “Expendables 2″ already has surpassed the original’s total overseas gross in holdover markets Italy and Russia, with $4.3 million and $14.1 million, respectively. The sequel launches in Australia, Brazil and Germany, starting Aug. 30.