2x drop not entirely increasing drop rate for area bosses?

Most area bosses have atrocious droprates to begin with. However when I was on 24-hour 2x drop, I found quite a few double drops from some, including Kimera. I even found a few scrolls in a row from, along with equips from Seruf, which usually almost never gives me anything compared to other area bosses.

In the end, it's all just luck.