Are the files on the web for the offline installer correct? Some parts seem to download the same file again?
Part 11 seems to be the root .exe again? Did they publish two sets of links?

Part 1 and 11 seem pretty identical to me.
https://i.imgur.com/E7bj5bE.png

It looks like they pasted the same files twice indeed?

You can see in your screenshot there's 32 bytes of difference in the size (which is the real size, the size on disk comes about from needing to round up to the minimum sector size for the last bit of data ).

Both EXEs and both of the 118MB bin files download as the same files;
setup_dungeons__dragons_neverwinter_nights_2_enhanced_edition_rc8_(83579).exe
and
setup_dungeons__dragons_neverwinter_nights_2_enhanced_edition_rc8_(83579)-9.bin
respecively
So, I'm not sure what the difference is other than that 32 bytes,

I see the file in the Extras in GOG Galaxy, but I've clicked it like 20 or 30 times and it will NOT download. It is listed as 1, 64 GB file in GOG Galaxy

All my other ganes's extras seem to be downloading just fine. But not this.

Yeah, it doesn't seem to be working from Galaxy at the moment; I've experienced the same. You're gonna have to download the installer from the website instead, and only the first 10 files; it's a 32GB download (That's what it says when you go to install it from Galaxy), and I believe the team may have accidentally posted the install files twice, even though for the second set, the exe and final bin seem to have a 32-byte difference from the first set. They're the exact same files otherwise.

Edit: spelling mistake, removed an extraneous instance of "the," and added a "for," between "though" and "the second"

I had some time to kill so I downloaded and installed both versions (1-10 and 11-20) and they seem to be pretty identical.
The version metadata displayed on the main menu both is the same:
Version 1.110 (1019) (FINAL) NETWORK COMPATIBLE (1765) Jul 12 2025 - 23:52:33

Do you have GOG Galaxy installed ? Because if you do and you installed it to the Galaxy install location, Galaxy will see the install and "fix" it to whatever it should be. This is generally the "correct" behaviour because it enables Galaxy features and Galaxy sometimes gets updated first if a game is large and expected to cause heavy load, but it does make these kind of comparisons difficult.

I don't generally use galaxy. I tend to buy the games on GOG just for preservation.
So these were the downloaded offline installers.

Any updates?