I think its the present ayu comforting the past ayu, and the present ayu is the one "treasuring" the other, I guess it's like saying how the present her treasures her past, no matter how it's been. She was chasing the past ayu for the front part, so it's like symbolizing how she can face up to her past now? I think it's the past ayu who disappeared in the end, so it's like just the present ayu reflecting on the past (which is not really there).
Don't know, just speculation on my part~
