U.S. producers of steel rebar undercut each other on price and are not hurt by imports from Mexico and Turkey, foreign firms told the U.S. International Trade Commission on Monday as they fought a push to slap duties on their steel. U.S.-based producers have complained of a doubling of imports between 2010 and 2012 and launched a trade dispute that could end in import duties as high as 67 percent on reinforcing bar used to reinforce concrete.