Sounding out a double-stop over the change of string is a way to practise a ’round’ bow in string crossing.
In performance, make the crossing between strings slightly faster, to avoid sounding the double-stop.
Experiment with how slow and steady you can make the string cross while maintaining clear articulation.
This excerpt is Bar 18 from “Sicilienne and Rigaudon” by Kreisler.
From Violin Bow Technique – purchase online at Twofold Media