This is my interpretation of the story so far:
I think the Seonwoo we follow in Chapter 1 is the Hunter-world Seonwoo, while the Seonwoo shown in Chapter 61 is the original Earth Seonwoo.
This is based on the following clues:
In Chapter 1, Seonwoo already has:
•a Hunter ID,
•the Happiness Management Clinic,
•an apartment,
•and an established life in the hunter world.
This suggests that someone had already been living there before the protagonist became aware of it.
In Chapter 61, we learn that the original Earth Seonwoo was transported into the game world when he was 9 years old. He spent 20 years there, eventually built the Happiness Management Clinic, and lived a quiet life.
My theory of the timeline
•Earth Seonwoo (age 9) is transported into the game world.
•He grows up there for 20 years, creates the Happiness Management Clinic, and becomes the Seonwoo of that world.
•After those 20 years, he returns to his original world.
•At the same time, the Hunter-world Seonwoo is sent to the game world.
•Because of the sudden transfer, the Hunter-world Seonwoo loses or confuses his memories and believes the game world was only a fictional game he played.
•This Hunter-world Seonwoo is the one we follow in Chapter 1, which explains why he already has an apartment, a Hunter ID, and a clinic, but doesn't recognize them.
•The Earth Seonwoo's perspective is what we see in Chapter 61, revealing what really happened 20 years earlier.
Conclusion
Based on this interpretation:
Chapter 1-60 follows the Hunter-world Seonwoo.
Chapter 61 follows the original Earth Seonwoo.
This theory also explains why the Seonwoo in Chapter 1 doesn't know Lee Jehee personally—because while the Earth Seonwoo was living quietly in the game world, the Hunter-world Seonwoo was living his own separate life until the two worlds became connected.
We are seeing the perspective of the other seonwoo, so the one we see in Chapter 1-60 is still alive, after all jehee turn back time. (=・ω・=)
IN MY THEORY ONLY....let is che d aq maka tulog kakaisip sa 61