Superior and Duluth will join in the legal battle against the makers and distributors of opioid drugs.The city councils for both jurisdictions voted Monday night to hire the same law firm Keller Lenkner LLC to represent them in the suit, seeking damages for a wave of addiction that has swept through the nation, saddling cities, counties and states with hefty response costs. In all, about 1,400 local units of government have filed claims against the opioid drug industry to date, and Seth Meyer, an attorney for Keller Lenkner, said that number continues to grow.