I just bought the Atomic edition here. I got both mods to work by extracting to the game directory, even changed the directory to Duke3D. When I play it, I'm stuck playing shareware, so only have the 1st episode unlocked. Did I overwrite something I wasn't suppose to?

Figured it out. I replaced the .GRP file with the once that came with the High Res Pack. It's working now.

which version of HRP? I downloaded the latest 7z file but there ain't no .grp file.