Nycto's already covered the increase in complexity this will cause. When you're running multiple protagonists, it becomes extremely important to ensure the characters stand out from one another (the chapters shouldn't feel like they're all the same). You could try having different fonts for that chapter, or a different background color, to make it easier to visually understand who's PoV you're looking through. Additionally, you may want to invest into a journal where each character's details are found (to help people returning to the story after a break).
Having two concurrent storylines is a major pain, consider having the second character more like a 'quest' character. You take a break from the main story, and switch to the second character's self-contained chapter, during which some decisions can be made that affect the main story. This can reduce complexity significantly.
Narrative wise, both characters have to be meaningfully different, a good cop and a bad cop for example, so that they can tease out different reactions from the same story element. Their differences through their actions should be visible.
There was one story, Sethaniel's Creature 2, where having three or more characters available at the same time had quiz-esque mechanics (one guy could hack a PC, while another just used the password). That was an interesting design framework, but beyond that, I'd be hesitant to offer the option to switch amongst PoVs during the same chapter, it just makes things waaaay to complex to be worth the payoff. remember, most of the alternate things you've coded won't be visible in one playthrough, and a player can breeze past never realizing how much they've unintentionally skipped. In that regard, CYoAs that are not full fledged Steam releases suffer from a lack of being replayed, and you just have to roll with it
Hope you found something useful in all this, all the best for your story.