https://www.techradar.com/reviews/kobo-elipsa
"When used horizontally, an ebook divides into two pages on screen (resembling an open book) thanks to the space available, which might be preferable to some users."
I'm surprised, since I saw no mention of it elsewhere. Also I wonder whether it is an option or an obligation. Anyway, it makes sense since our eyes aren't best adapted for reading long lines.