I believe how NPCs work is usually you have a set of Hero NPCs which give you missions and can be immortal, like Aela in Skyrim. Then you have some minor, killable NPCs which can also give you missions and then you have everyone else which, theoretically should consist of randomly generated parts, but it's more of randomly generated NPCs from a pool of pre-created ones. (Probably due to the resources and processing power it would take to actually created randomly generated NPCs out of parts. Especially in something like Cyberpunk 2077 where you have lots of different cybernetic implants and stuff.) Now, you can REDUCE the likelihood of duplicates by simply increasing the pool of randoms, but, even then, especially if you increase the number of NPCs to help a busy, bustling city FEEL like a busy bustling city, then you increase the chances of duplicates. But, if CP2077 is in pre-alpha, again, by the time it comes out, the Random NPC pool could increase to the point where the likelihood of running into duplicates is rare, or should be. Of course, there's a chance that some bugs might pop up that accidentally increase the chances of duplicates, but who knows.