At the same time, that Loki of Midgard is slumbering, Loki the Cosmic trickster also returns back to his body in the Primordial Garden.
The replica that he created is not entirely a replica.
He just let Peter believe it to be so. Because it would be easier to make him believe it was the replica. And he had no intention to correct Peter thought.
Peter was actually inside the real Primordial garden. The only difference was that Loki brought his disciple soul into it.
The Primordial Garden did not rest in only on plane of existence. One could enter it in many ways and as such the garden has many forms
One of it is in Soul form.
That is where and how Peter had arrived. The Soul form of the Primordial Garden which is not that different from the real Primordial garden.
As such, there were many things that had to be obscured.