Elena and Ana Bogdan | Are they or just the same last name?
Don't know about them, but Angie and Jenifer Widjaja fit this description (and are from "half a world away" from eachother).
Another interesting thread might be the relatives of athletes from other sports who played pro or college tennis. For example, former Major League baseball pitcher Bill Gullickson is the father of Carly and Chelsea. And another ex-pitcher (Phil Bradley) is Megan's Dad.