MIAMI — Garrett Cooper doubled, singled and hit a go-ahead three-run homer in the eighth inning as the Miami Marlins beat Pittsburgh 6-4 Thursday night and extended the Pirates’ losing streak to 10 games. Trailing 4-1, the Marlins rallied against Pirates relievers Dauri Moreta and Carmen Mlodzinski in the eighth. Moreta allowed a leadoff double to Jonathan Davis and then walked Luis Arraez and Jorge Soler. Mlodzinski (0-1) relieved Moreta and gave up a two-run single by Bryan De La Cruz.