One of the links brings me to the Duke Nukem website, which has the text "Happy 20th Anniversary", among other things. I'm pretty sure it relates to Duke Nukem 3-D ... and possibly even retcons all plotlines relating to games that followed up on it.
I suppose I'll keep you all informed on this, but I'm game for an All-Apogee-releases collection from 1998 instead. It'd fill in the remaining gaps I have in my collection, and it's a great way to get those first three missing Duke episodes, which my father had, but I didn't.