Probably a scene where there sky (background) is too bright and the buildings (foreground) is normal lit. If i take a single exposure with the buildings correctly expose, the sky will be blown out, if i take a beautifully expose sky, the buildings will be terribly underexpose.
but from what you said, underexpose each image by 1 stop, won't it make the overall picture dark when i put the 2 frames together and print/scan?