The Great Isaiah Scroll, the oldest nearly complete book from the Hebrew Bible, dating back to the second century BCE, was originally created as two separate scrolls. The first 33 chapters were written on a different parchment to chapters 34 -70. And the scribes were different too.

https://www.timesofisrael.com/the-oldest-complete-biblical-scroll-ever-found-was-originally-split-in-2-scholar-finds/