If you want to enchant a stack of pumpkins or mob heads in the anvil all you need is one book.

Steps to Reproduce:

1. Place an anvil.
2. Obtain a Curse of Binding book and a stack of carved pumpkins/mob heads.
3. Place the Curse of Binding book and carved pumpkins/mob heads into the anvil.
4. Enchant the carved pumpkins/mob heads with Curse of Binding.

Observed Results:
The entire stack of carved pumpkins/mob heads is enchanted with Curse of Binding.

Expected Results:
Only one carved pumpkin/mob head should be enchanted with Curse of Binding.