Replacing and Copying Spellbooks
A wizard can use the procedure for learning a spell to reconstruct a lost spellbook. If she already has a particular spell prepared, she can write it directly into a new book at a cost of 100 gp per page (as noted in Writing a New Spell into a Spellbook, above). The process wipes the prepared spell from her mind, just as casting it would. If she does not have the spell prepared, she can prepare it from a borrowed spellbook and then write it into a new book.
Duplicating an existing spellbook uses the same procedure as replacing it, but the task is much easier. The time requirement and cost per page are halved.
What about the idea of a second completely new spellbook with completely new spells, thus having two different spellbooks of your own creation with different spells?
This could be great for not putting all your proverbial eggs in one basket as well as extending the number of spells available to you without the limitation of the number of pages of spells that can fit into a single spellbook.
There is nothing in the rules that prevents this. Most well-run wizards should end up with multiple spellbooks containing different spells by the time they reach mid-level.
There is nothing in the rules that prevents this. Most well-run wizards should end up with multiple spellbooks containing different spells by the time they reach mid-level.
When you kill the enemy wizard and take his stuff, his stuff will usually include his spellbook. Your wizard is free to use the dead guy's spellbook.
Actually, that's not true.
Arcane Spells :: d20srd.org