The Luke Bryan/Metallica twofer isn't necessarily something special devised for the opening of U.S. Bank Stadium. It's part of a trend in the concert business.

"It's efficient from a calendar standpoint and it's efficient from a cost standpoint," said Jason Wright, president of Live Nation Chicago, which is promoting Friday's Bryan concert.

Doubleheaders can happen if you have a window of open dates in a sports stadium — it takes several days to set up and tear down a stage — and two superstar acts that fit into the schedule.

This practice has been going on for the past five or six years, primarily at Chicago's Wrigley Field and Boston's Fenway Park. At Wrigley in June, there were two Phish concerts followed by a James Taylor/Jackson Browne show. In August, the Chicago Cubs' home will present Pearl Jam for two nights, then Billy Joel and Bryan on back-to-back days the following weekend without taking down the stage.

While money is saved on building and dismantling the stage — $150,000 to $250,000, estimates Minneapolis promoter Randy Levy, who is not involved with either show — Bryan and Metallica will use their own sound, light and video systems.

These stages are more generic than, say, the custom-made "Claw" used by U2 in 2009-11 or the stage for Beyoncé's current tour. But if it weren't for the adaptable stage, this Minneapolis doubleheader wouldn't have happened.

"It allowed Metallica to say 'yes,' " said Levy, "because they weren't even on tour."

Jon Bream