I was reading some violin sheet music when I came across something that looked like a slurred double stop. Here is an image:
The problem is that both double stops use the same fingers, but on opposite strings. Assuming first position, the first double stop uses second finger on D string and first on A string, and the next note uses first finger on D string and second on A string.
How can you move both fingers to other strings, under a slur, without playing a little bit of open strings?