A 19-year-old youth, formerly of Mauch Chunk, who was unaware until recently that he possessed an accessory kidney - three in all - underwent a rare operation for removal of two of the organs. Surgeons at Sacred Heart Hospital in Allentown took two from William J. Conroy's right side, not because he had too many but because one was diseased. They said it was the 28th such case in medical history.