Lore explanation for Multiple Clauds

The devs have stated that it's solely for gameplay purposes. Canonically, there is only one Claudette, only one Ash, only one Dwight, only one Adam, etc.

It's just done so anyone can play anyone they want and not be locked out because someone else picked that same Survivor.

This is something I actually find extremely interesting and fun to talk about, so let me explain (hopefully without ranting EDIT: I ended up ranting oh well. Read the history and then read the second explanation, the first is just a kind of offhand that some people have thought of before)

The place where survivors now find themselves in is not the real world, at best you can say it's sort of like a parallel dimension but really there's no other way to describe it than "The Realm of The Entity".

Most of what the entity is is an unknown mystery. Its motives, intentions, how it works mechanically / biologically is more or less incomprehensible and horror indescribable.

So already the answer is going great because we're admitting to knowing basically next to nothing.

However, there are a few things we do know and with what little information we have we can cobble together a reasonable explanation.

History / background info.

The entity, which is not exactly on the same plane of existence as the real world can actually pull survivors and killers from different time periods (and also dimensions, technically / supposedly). One of the very first characters we are introduced to: Benedict Baker is one of the first indications of this messed up chronology as one of his diary entries is dated 1956 but a few entries later there is a new date: 1896, which is repeated on many of his other entries about the entity, the bloodweb, the heartbeat, etc.

Benedict Baker's journal entry about The Hillbilly specifically makes little sense as the first hand-held, motorised Chainsaws weren't invented until in 1918 and thus a man that was taken into the Entity's Realm in 1896 should not know about their existence, let alone how to use one.

What we can gather from this (and basically what I just took a long time explaining even though the devs confirmed it in a sentence) is time does not exist in the realm of the entity. If we go back to one of the first sentences I said "the place where survivors now find themselves in is not the real world" you can also use this to infer that this place is not bound or perhaps only loosely bound by the same laws that govern our own reality. Laws about Time, Space, etc.

So now to answer your question there are two explanations for this, one is simple, and one is far more intriguing and thought provoking.

First explanation

The first is that the entity pulls from different dimensions the same person, this also neatly enough explains the different outfits that exist in the game they are all different versions of the same person. Take Dwight for example, two Dwight's spawn in a trial: one is wearing "The Great Gas Jockey" outfit and another is wearing the "Mr. Elf" outfit. This is in fact the same person Dwight Fairfield but from two different dimensions or times in two different dimensions, one where he was working as an employee at "Phil's Petrol" and another where he "he secured a part-time job at the mall. [over the holidays]"

However, this theory doesn't fit well since in every survivor's bio we are given more or less the circumstance or single canonical moment in time that they disappeared. Or were "taken" to the realm of the entity This was the one for Dwight:

"One weekend, on a team-building exercise from his dead-end job, Dwight's boss led them deep into the woods before breaking out his family recipe moonshine. Dwight remembered taking the first sip before waking up late the next morning all alone. During the night, the others had abandoned him. Once again, the laughing stock of the community Dwight tried to hike his way out of the woods. That was the last anyone ever heard of Dwight Fairfield."

Second explanation

The second which I believe is more reliable is a more science heavy explanation, and relies more on the lack of the existence of Time. Here's the best way to think about it: say you were in your room at home alone and then you walk out of your room. 5 minutes later, you walk back into your room and then walk out again. Thirty minutes later you walk back into your room.

Now take that same circumstance, and say time doesn't exist, throw it out the window. What happens? What is there to distinguish between you walking into your room 5 minutes later and thirty minutes later? Nothing. You walking into your room 5 minutes in the future and thirty minutes in the future is no longer separated by the time between because it no longer exists so you actually walk in at the same time

At that point you can't even call it the future anymore, because it's all mixed and mingled, it's the past the future and the present all happening at once. So the first Dwight is from 5 minutes ago, the second Dwight is from 15 minutes ago, the third Dwight is from 30 minutes in the future and the fourth is from now. Except there is no "now" because there is no time. And to each one of those Dwight's "Then" is "now" and they are all experiencing it in the same moment at the same exact "time".

So basically:

tl;dr Time does not Exist.