Thanks for all your help everyone, I appreciate it. However, I'm still not sure that I've explained the situation clearly (I find it hard to put computer operations into words sometimes) so I'm going to try a demonstration with pictures this time! Let me know what you think:
In this first image, observe the clip in the clip pane. It's 2 bars long and the 2nd bar is empty. What I want to do is copy the notes in the first bar to the second bar. As you can see, I'm selecting
all of the notes in the PRV. My selection doesn't overlap the clip boundary in any way:
In this next image, you can see the result of this selection in the clips pane. The whole of the clip is selected:
Now let's try again, but only selecting some of the notes:
As you can see in the next image, the entire clip is
not selected. Only the part of the clip that encompasses the selected notes is highlighted:
Because only the notes are selected and not the entire clip, I can paste these copied notes elsewhere in the clip without a new clip being created and overlaid on top of the first clip.
So the behavior I'm getting is that when I select
all of the notes in a clip, Sonar selects the entire clip as a unit. When I select just
some of the clips, Sonar will just select those notes, and highlight only the part of the clip that the notes encompass.
I hope this is clear now. If you aren't seeing this on your system, it has to be a setting that I have somewhere, although I just can't seem to find anything it might be. I really need to get to the bottom of this!