Elvira built upon a superb opening-round 64 to take a solo lead at Celtic Manor. The 34-year-old made six birdies as he set the halfway target at 11 under.
For most of Friday, Elvira led the European Tour at the same time that his younger brother, Manuel, was leading on the European Challenge Tour. Manuel was later overtaken by France's Frederic Lacroix.
"It's unbelievable," Nacho Elvira said. "He's my brother, he's 10 years younger, he turned pro a couple of years ago.
"He's been playing great. I saw this morning he started with four birdies in a row and I didn't want to look anymore.
"It's awesome that we are both 11 under and leading, it's interesting -- that must have never happened before."
Norrman got off to a shaky start, making a bogey and double bogey on the front nine, but the Swede picked up the pace at the turn, carding five birdies on the back nine.
Elsewhere, Japan's Masahiro Kawamura raced up the leaderboard as he carded 63 on Friday to sit three shots back in third place following an opening-round 71.