I emailed Philip Kaplan, who is the founder and one employee of DistroKid.com. I asked how to go about uploading the other songs of "music from Duke Nukem 3D" so my trial uploaded song would be included in the album. I'll let you know what/when I hear back. I imagine Mr. Kaplan is very busy.
In the meantime, I am going to upload my updated recordings of the music from Major Stryker. For years I have been putting this sort of thing off as it's like living in the past -- and it takes me away from creating new things. But, I actually enjoyed reworking the Stryker songs. Almost as much as I enjoyed working on them twenty years ago.
The original songs could have no more than 9 note polyphony, which called for lots of editing and searching for overlapping notes. Before updating any of the songs, I decided to try to maintain the feel of the song, meaning I wouldn't add new notes, instrument parts, melodies/harmonies and such. But, I did add "verses" on some, and endings.
I'll let you know how this goes.