More help to my theory.

In that case there is only ONE person on the present similar to little Elle.
...Who? :)

Yes because they are the ONLY ones in the world.
So applying Occam´s Razor the simplest explanation is:
They are the same.

I've had a look at them both. Rinoa has black hair with highlights. Ellone has brown hair. That's where it ends i think.

Of course.
But Rinoa´s personality matches little Elle better.
Occam´s Razor dictates the answer
To a point, i agree. When you first meet Rinoa, shes immature, smart and brave. But i think the reason she's this way is because of her hate for her father. Later on she begins to grow up a little bit, and by the disc 3 midway. Shes mature, smarter and willing to be frozen in order to keep the peace or something. Ok i'll give you this.
Disc 1-2 Rinoa is similar to past Ellone.
Disc 3-4 Rinoa is similar to present Ellone.
Still don't think they're the same though.

Good to know you discuss instead of comment ChickenHeart
I do what i can!