Alex Walsh is a swimmer from Greenwich; Kate Douglass, a swimmer from Pelham. But now these young women are friendly rivals on the University of Virginia swim team and on Team USA at the Summer Olympics. On Tuesday, July 27 at the Tokyo Aquatic Center, Walsh and Douglass took the silver and the bronze respectively in the women’s 200-meter individual medley, finishing at the wall with a dramatic flourish. The 400-IM gold medalist Ohashi Yui of the home country won the event to sweep the IM.