485. Seth means another church here than the one previously depicted by Seth, in Genesis 4:25 (see §435 there). Churches whose theologies are different can be called by the same name, as verses 17, 18 of the last chapter show. Two churches mentioned there were called Enoch and Lamech, while two others in verses 21, 30 of the present chapter are likewise named Enoch and Lamech.
Secrets of Heaven #435
435. The meaning of the human and his wife as the new church previously symbolized by Adah and Zillah is not something anyone can know or figure out from the literal sense, because before now, the person and his wife symbolized the earliest church and their descendants. But it can be seen from the inner sense.
It can also be seen from verses 3-4 of the next chapter [§485], which say again that the human and his wife gave birth to Seth (though in completely different words), where he symbolizes the first generation to inherit the earliest church. If the symbolism were no different in this verse, there would be no need to repeat it. In the same way, the first chapter told of the creation of the human, the earth's vegetation, and the animals, and the second chapter did likewise. This was for the reason already given [§89], that the first chapter spoke about the creation of the spiritual person and the second about the creation of the heavenly person. Wherever this kind of repetition concerning the very same person or thing is encountered, one occurrence has a different meaning from the other. What the meaning is can never be known except from the inner sense, although the actual thread of the story confirms it.
Besides, human and wife, wherever they appear, are words symbolizing the church under discussion there, in its role as a progenitor.