When indexing a phone book there are multiple John Smith. Do I add all or just 1 John Smith?

You will index the first John Smith, then skip down to the next unique name, like John A. Smith.

From Project Instructions/What To Remember About This Project:

Index each unique name. Some names may be duplicated. When names are exact duplicates, meaning that all required fields are the same, index only the first instance of the name listed. Skip the other exact duplicates and then index the next unique name. Unique names include names with different middle initials and different name spellings or where the other required fields are different.