Fannie Mae has paid $1.5 billion to a dozen banks that manage its massive home loan portfolio so that it can hire a companies it thinks will do a better job with loans in danger of foreclosure, according to a government watchdog report released Tuesday.The report, issued by the inspector general for the Federal Housing Finance Agency, concludes that Fannie Mae is probably contractually required to pay a breakup fee in order to move these loans, but that in many cases the government-backed mortgage giant appeared to be paying millions of dollars too much.