The Massachusetts State Police are backing off an earlier assertion that the two suspects had robbed a 7-Eleven in Cambridge. “The most accurate statement is that we’re investigating whether they were involved in an armed robbery in a 7-Eleven,” said Dave Procopio, a spokesman for the state police. “Initially we came out and confirmed it for you, now I want to go back and double check it,” he said. “I want to qualify that further to say we’re double-checking.”