Credit-reporting giant Equifax has fired at least two dozen employees for working undisclosed jobs, and used extensive work-history records it holds on more than 100 million Americans to catch them, according to documents and interviews with people familiar with the matter.In one of the latest signs of corporate America trying to regain control of an increasingly remote workforce, CEO Mark Begor this week informed employees that some of their "teammates" were fired for having "a second full-time job while maintaining their full-time role at EFX," which is the ticker symbol for Equifax.The crackdown was the result of an investigation that unfolded in recent months conducted by Equifax employees, including HR and cybersecurity, according to a document seen by Insider.Those leading the investigation combed through work histories and activity records for more than 1,000 employees and contractors, according to an Equifax employee who was not authorized to speak publicly and internal records seen by Insider.Some employees may have even dialed into interviews with Equifax, conducted as part of the probe, from another job site, she said, including one who worked as a nurse, and another who claimed he was at home while sitting in what looked like an office cubicle."