bkev said:

If I read this correctly Fox took back the print that the Library had by force and LFL requested they store the 1997 edition which they refused to do. What's funny is if they had taken that, they probably wouldn't have a single film version on-file now and instead be forced to keep a digital copy of the 1080p files or even just simply the blu-ray.

But the LoC Librarian writes:

"When the request was made for STAR WARS, Lucasfilm offered us the Special Edition version. The offer was declined as this was obviously not the version that had been selected for the Registry."

"The Library of Congress does hold the original release versions of STAR WARS, THE EMPIRE STRIKES BACK and RETURN OF THE JEDI, but these 35mm prints were acquired as copyright deposits in March 1978, October 1980, and June 1983 respectively. All three are classified as archival masters and as such cannot be accessed for viewing/research."

Which leads me to believe the LoC does not have the SE and does have the originals, albeit closed to the public.