I've experienced unexpected behaviour with other objects than [vst~]. Today, for example, I was using the [M4L.pan2~] for panning a stereo track/[buffer~]. However, the effect it produced was an unexpected, gentle spatialising yet when I detached & re-attached the signal to the left inlet [M4L.pan2~] would produce perfect pan. Each time I loaded the patch I had the same problem/result so I gave up and used two mono crossfaders instead!! In the past, I've fixed broken patches just by replacing an object with an identical, new one; for this reason, I prefer to create new objects rather than copy/paste existing ones. I think the reason for this is down to how each object is coded and the functions they perform, you may well need to create a new [vst~] for each instance to work around this predicament.