ZDoom

fixed

Funny enough, the latest GRPs (and also the GRP files from the 2015 anthology pack from what I can tell from GRPSCAN.C, I had no idea those GRPs were different from the Megaton ones) actually fix this issue by not using USER.CON

Which is ironically why Duke it out in DC wouldn't work for him, as scriptname "DUKEDC.CON" was missing in Raze's GRPINFO.TXT for the entry for the new GRP file

This auto-extraction by the DOS EXE has been the prime reason why Duke mod distribution has been such a mess. I really have no idea what they were thinking when implementing it.

Posting this here because it came up on discord and similar issues have come up before for other source ports.

If when you launch those expansions those you only see the episode Shrapnel City, then it is likely that that you have the file USER.CON in the same folder as DUKEDC.GRP or VACATION.GRP. If so delete it (USER.CON is already contained inside DUKE3D.GRP so it's not needed to run the game, from my recollection running the DOS game automatically extracts it so you may need to delete it again, or better yet make a separate folder for the DOS version)