Correction, the notes don't materialize on the balls, the balls are in between a note and a wall or both notes that have been hit at the same time. The note still has to be hit at a different time though. With this in mind, you can hit two notes with one ball and not change its trajectory.
Found an odd thing, if you can get a note to materialize on a ball
(it has to be hit at a different time than the time that ball entered)
The note acts as if it was hit normally.