Swap 'cool blue and silver tones' for 'warm amber and rose tones' and change 'ethereal periwinkle sky' to 'golden dusk sky.' You could also change 'luminous crescent moon' to 'low setting sun' so the light source itself shifts from night to golden hour.

Move 'solitary figure standing on a cliff edge gazing at stars' to the front of the prompt and describe it with more detail, like 'a woman in a flowing coat standing at the cliff edge, gazing up at the stars, sharply lit against the horizon.' Then demote the portrait by shortening it to something like 'faintly overlaid with a man's silhouette' so it reads as the secondary texture rather than the primary shape.

Keep the double exposure structure and the phrase 'cool blue and silver tones' constant, then rotate the landscape half: swap 'cliff edge gazing at stars' for 'forest clearing beneath a full moon,' 'ocean shoreline under a starry sky,' or 'mountain ridge wrapped in fog.' Changing just that one setting phrase each time gives you a matched set with the same silhouette treatment and palette but a different scene inside it.