INCREDIBLY EXTREMLEY SUPA DUPA Rare Hardcover Original Captain Underpants (sorry 4 caps)

So I was browsing Dav Pilkey's oldest website on the Wayback Machine, and I found out Captain Underpants 1 had a hardcover version (same probably went for the other books til book 8 where the hardcovers became more common), i thought it was the collectors edition but that came in 2005 and the page was from 1998, i did more research and i couldn't find more info on the hardcover version of the first book.