Yo! Who else knew about the secret fight with duskveil and scorpion lord

I was doing a boss rush so I can get the wukong stance as my permanent stance. In chapter 4 secret area I went straight for duskveil because he's the final boss of the area but I didn't know that scorpion lord would join in on the fight, he was like "give me a hand let's take him down together"🤣. That literally blew my mind ong 🤣, I thought you could only do this in chapter 2. The fight was amazing tho.