That's... strange, I've never heard of that issue before. I've so far been unable to replicate the bug, but if I do manage to work that out, I'll see how I can go about fixing it.

In the meantime, are you certain that it's the same list every time, or are you just getting very similar lists each time? With the amount of items that show up in the Black Market in this mod, especially lategame, each item has a somewhat high chance of spawning. An easy way to check this would be to find a modded weapon in the black market, close & reopen your save, and check if you can find that specific modded weapon again.

Yes, you're right. The list of goods is being updated, I just didn't notice it. I usually buy only special weapons from the chief, and I often had them repeated.