Ack! That's a lot of lost data. Now that I'm comparing the output of exiftool side by side for the images, I can see the difference. Is there any way that data is still in the image file? Is there any possibility of getting it back? I've imported all my photos into F-spot, unfortunately, so if it's gone, it's gone for all of them. I do not have any originals (except the ones I haven't imported since I discovered this issue.

Thanks for all your help, Phil.