====== I have an extra spellbook that should not be there. ======

You have probably added a feat that belongs to a different class (using Bag of Tricks or other similar mod).

So far, I know of these:

  * Enhance Potion - Alchemist
  * Spontaneous Healing - Cleric
  * Scroll Mastery - Wizard
  * Scroll Specialization - Wizard

If you just remove the spellbook (with Bag of Tricks), it will soon reappear (usually when you save or load). 

**Solution:** You need to first remove the feat and then also remove the spellbook.