The transparency blend space is cmyk on all and the image has no effects on it. But when I move it from the one page to the other it goes from darker and more contrasted to lighter and less contrasted. Copying and pasting as well as taking the original and replacing does the same thing.
Is the image cmyk? It sounds like the image is RGB and that one page has transparency and the other doesn't, so it's only being affected by the flattener on one page.