By David Morgan and Aruna Viswanatha WASHINGTON (Reuters) – Two federal judicial panels on Tuesday delivered conflicting rulings on how the government subsidizes premiums through President Barack Obama’s healthcare law, creating more uncertainty over signature legislation that has been dogged by challenges from Republicans and other conservatives. The rulings, handed down by appeals court judges in the District of Columbia and Virginia, could lead to a new showdown over Obamacare before the U.S.