Yeah, that's where I'm at too.
Also, when did Tulpa Diane begin to... exist in the world? Was the real Diane raped and taken into the Lodge and the Tulpa Diane created with real Diane's memory? Was the Tulpa Diane created and raped afterwards? Was Diane always a tulpa? I'm confused on the timeline of this- Cooper's doppelganger's presence in our world has a fairly clear cut explanation by comparison.
Diane was raped then taken to the room above the convenience store. Her Tulpa was made there I believe.
The real Diane's fate is unknown, and I assume that's why she is connected to Naido now. Whatever happened to her.
Dougie seems like he wasn't a Mr C double, but remember Dougie had an accident. And people expected a weird behavior from him (to the point of not being alarmed at seeing our Dougie's behavior).
So it's possible the original Dougie had suffered memory loss, potentially caused by Mr C himself to avoid having another "Cooper" trying to steal his spot.
We did see Dougie was kind of rotten, when he turned back into a seed, he had a lot more darkness, and remember he did vomit some garmonbozia. The debts and cheating was part of that I assume.
But without memory I guess he wasn't THAT bad.