Im not into notes and not into US note.

http://www.banknotenews.com/files/tag-united-states.php
http://www.numismaster.com/ta/numis/Article.jsp?ad=article&ArticleId=20099

Just posting another reference for banknote,silver and gold certificate that it might have a effect on coins during those years.

The change in law and design of banknote may also result a variety in coins just a comment.