The state’s highest court upheld the first-degree murder convictions Wednesday of two men in a 2001 double murder in Mission Hill, authorities said. The Supreme Judicial Court rejected the appeals of Terrance Brown and Nathan Rivera, both 31, Suffolk District Attorney Daniel F. Conley’s office said. The men were convicted in 2006 in the fatal shooting of two 20-year-old roommates, Roland Chow and Karen Young, inside the victims’ apartment. The assailants were looking for drugs and cash, prosecutors said. Brown and Rivera are serving life sentences.