Here are the Special Edition Library of Congress records:
1997 - Star Wars A New Hope Special Edition
http://lccn.loc.gov/97510343
Acquisition Source: Received: 4-1-1997; viewing print; copyright deposit--RNR; Copyright Collection.
1997 - Empire Strikes Back Special Edition
http://lccn.loc.gov/98502262
Acquisition Source: Received: 3/17/97; ref print; copyright deposit--RNR; Copyright Collection.
1997 - Return of the Jedi Special Edition
http://lccn.loc.gov/2006642053
Acquisition Source: Received: 5/23/1997; viewing print; copyright deposit--RNR; Copyright Collection.
Weird that ESB was submitted first. But it was the least modified.