This is really bad, but I remember a YA book that used dual viewpoints (boy/girl) and past/present. What I don't remember whether is whether the present story line was written in past or present tense. I really liked how everything dovetailed at the end perfectly. But sorry, I don't remember either title or author.
Then there's Moon Over Manifest, which has two historical periods being covered and it's superbly done. One of my favorites.
Vijaya