I'm not sure what chapter but they definitely cleared that up in a round about way.
Current Raeliana was reincarnated from the modern world BUT SHE WAS SUPPOSED TO BE REINCARNATED A BEATRICE
BUT THE ORIGINAL RAELIANA placed her soul on Beatrice's body so when the modern world girl died and was supposed to reincarnate inside Beatrice's body it was already occupied by the Original Raeliana's soul so the modern world soul had no choice but to find a body without a soul which is RAELIANA'S BODY so that's how she got there, so ever since the beginning her soul is already unstable bc she was not meant to be in Raeliana's body.
Hope this clears that up . ヾ(❀╹◡╹)ノ~
In the past chapters Ioa said that in the story the God- who she refers to as the playwright assigns the right souls to the character's body im the story.
The OG story finished so everyone's soul already fulfilled their role so their souls are 'gone' so for the story to STILL go on the Playwright assigns another soul to the bodies.
This time I think Realiana reincarnated first *I think she has memories of her past life bc she knew what would happen to her* BUT she wanted to avoid that so instead of making an effort she resorted to placing her soul to Beatrice's body.
So around this time when the SUPPOSED SOUL that was assigned to Beatrice's body is going to reincarnate BEATRICE'S BODY was already occupied by Raeliana's Soul so the soul had no choice but to go to RAELIANA'S BODY.

I don’t know how I can hide the text sorry . I Want to talk about something ;)
So I think about Beatrice. I don’t know if it’s true but why not >.<
Maybe the réal Raeliana changed her soul in Beatrice body. Because when Raeliana reminder the past she makes something with her finger and Béatrice too.
That’s why, my theory is : in Béatrice body is the real Raeliana
What do you think about this ?? (●'◡'●)ノ
Sorry for my English ╮( ̄▽ ̄)╭ i hope you can understand