" some souls might be incarnated in two or three separate lives simultaneously on earth".

That's what seems to be happening in David Lynch's film Mulholland Drive. The two main characters, distinct persons on Earth, are at a deeper level the same person/soul. In relation to your content here, you might find my article about it interesting:

https://medium.com/@graham-pemberton/the-genius-of-david-lynch-mulholland-drive-9d88313758c3