Good grief just when I think I've heard it all.
. . . Au contraire mon frère. There's so much more than you might even be aware.
Clear: Adam and Eve were already to reproduce according to the Bible at Genesis 1:28.
Adam and Eve were married, husband and wife - Genesis 2:24.
The two verses you mention don't appear to be speaking of the same thing since the male and female in Genesis 1:28 are said to be created simultaneously and are given dominion over all the creatures of the earth, while in Genesis 2:24, the female has just been created from the rib of the first human, who (the first human), preexisted her. They weren't created simultaneously, and the second one is treated not as part of the original creation, but as an afterthought, a later addition, for the sake of the first human.
Furthermore, the first human, and the woman created from the rib, are consigned to a "garden," such that they might not even be aware of, or have access to, all the other creatures outside the garden. After the first, or original, sin, they're actually exiled from the garden, and placed amongst all the other creatures on the earth (possibly to include the males and females noted in Genesis 1:26) potentially explaining where Adam and Eve's offspring find mates other than their sisters.
Neither Adam nor Eve were ever offered immortality just everlasting life on Earth 'if' they obeyed God.
The technical, scientific, meaning of the word "immortal," merely means that the living organism isn't subject to death from its own biology. Something acting on the biology of the organism must cause its death. The original living organisms on planet earth were all immortal. Science says only with the evolution of, get this, sex, did programmed death, death as part of the nature of the biological cell, arise.
Biblically speaking, Adam and Eve were immortal so long as they remained in the garden. It's the expulsion from the garden of immortality that cause them to begin to age, leading to inevitable death.
If they were immortal, then breaking God's Law of Genesis 2:17 would Not have brought death.
Again, "immortality" merely means they won't die unless something acting on them from outside their immortal bodies causes their death. Breaking God's law, i.e., eating from the tree, that is, having sex, led to death becoming a natural part of their biology and the biology of the offspring of their unlawful mixing.
There was No post-mortem penalty, No double jeopardy for either dead Adam nor dead Eve. They just ' returned ' back to the dust of the ground - Genesis 3:19
Their formerly immortal bodies senescenced and died. But the soul can't die. It's just that without a body it's in a real pickle.
John