Yes, I did lose sight of the specific issue when I got to Calvin. I saw that he acknowledged guilt due to Adam, but as you point out, this doesn’t distinguish the two positions. It’s not, according to Calvin, that we are guilty for Adam’s sin, but that we are created guilty because of Adam’s sin. So from conception each person is “guilty not of another’s fault but of their own” because they were created as rebels due to how Adam corrupted human nature.
Augustine wasn’t content with that option since he thought it made God too directly responsible for sin. Either God is creating rebel souls, or if the corruption is located in the body instead of the soul, God is ensuring the corruption of good souls by placing them in rebel bodies (see his The Nature and Origin of the Soul 1.34 and 1.6, among many other relevant chapters). For Augustine it was necessary to show each human’s culpability for the condition they were born into, and he did so by claiming we were all present in Adam and sinned in Adam.
Certainly there are alternative views, including among those within the Augustinian camp on original sin. Many Augustinians don’t follow him on the need for infant baptism. Most recognize that modern biology makes it untenable to view males as containing all their progeny in their loins. Many take a different position on how God creates each human soul. To be Augustinian does not need to mean sharing all of Augustine’s views.
But I haven’t seen evidence here that serious scholars read Augustine as holding these alternatives. Calvin was not writing to exegete Augustine: he was giving his understanding of Christian doctrine. He quoted or referenced Augustine and other church luminaries to support many points, but felt no need to itemize where he disagreed with each one. The Reformed confessions, likewise, are attempting to distil Christian teaching, not Augustine’s thought.
When Reformed theologians do trace the history of original sin, I’m often impressed by their care to get Augustine right rather than read their own views into him. For instance, Louis Berkhof notes that Augustine shared the “realistic conception of Tertullian” in which the whole human race is really in Adam so that all “sinned when he sinned and became corrupt when he became corrupt.”[1] But original sin “is not merely corruption, but also guilt.”[2] He also notes that Augustine sometimes comes close to the idea of Adam as representative, that his idea of “imputation” was not fully developed, and that he emphasized how the sexual act propagates Adam’s sin. He gives a good taste of the complexity of Augustine’s view without watering it down to a few ingredients that fit in his own system.
I am still interested in seeing how some read Augustine differently. If you have sources for your V1 and V2 positions that show how they are present in Reformed scholarship, I’d be grateful.
[1] Louis Berkhof, Systematic Theology (Grand Rapids, MI: Eerdmans, 1938), 237.
[2] Berkhof, Systematic Theology, 244–45.