Several months ago, I managed to build a full district set of 1976 $2 Federal Reserve Notes, postmarked on the First Day of Issue, April 13, 1976 -- Each of the 12 notes had the same stamp, the 13-star flag over Independence Hall stamp (Scott Number 1622):
http://www.panix.com/~clay/currency/1976-District-Set-1622.html
After a lot of work, I've built another set. This one is another full district set and each note has the same stamp -- In this case, the Americana Issue - Eagle with Shield stamp (Scott number 1596):
http://www.panix.com/~clay/currency/1976-District-Set-1596.html
Now,
that's crazy!