Liquidia (LQDA) topped Wall Street's second-quarter expectations Wednesday as sales of its lung disease treatment, Yutrepia, grew by double digits amid an ongoing rivalry with United Therapeutics (UTHR). Yutrepia and United's Tyvaso are inhaled treatments for forms of high blood pressure in the lungs. During the June quarter, Yutrepia generated $170.4 million in sales, growing 31% and beating the Street's…