NEW YORK (Reuters) - Kevin J. Martin, the chairman of the Federal Communications Commission, has privately questioned recent congressional testimony by the architect of a proposed merger of the nation's two satellite radio companies that subscribers would both pay the same monthly rate and receive significantly more programming, The New York Times reported. As he sought to sell the proposed merger of Sirius Satellite Radio (SIRI.O: Quote, Profile, Research) and XM Satellite Radio (XMSR.O: Quote, Profile, Research) to Congress, Mel Karmazin, the chief executive of Sirius, vowed last Wednesday that prices would not be raised and that listeners would benefit...