Thank you for the suggestion! We'll keep your suggestion in mind as we continue improving PureRef in the future. If we understand you correctly there might be some workarounds that could work in your case:
If it is mostly just that you want to keep the bounds the same between images, you could use
Zoom cropping /
Pan cropping to adjust the cropping within the existing image bounds.
If you want to retain the exact cropping between images with the same resolution you can use duplicate and then
Replace image which should retain the cropping of the old image.