System Configuration Console invalid node
It is true that you only have "one shot" with a computer and System 800xA v6 or later. Deployment of a new node "into a system" requires a "fresh" installation of Microsoft Windows. Reuse of nodes having experienced previous installations is intentionally blocked.
However, I believe your procedure should work since:
- AS2 has only been "deployed" into a system once
- The backup you restored to AS1 contained AS2
You did not rename AS2? Rename is supported, first rename the target computer, then update the name in SCC>Configure System.
I recommend contacting your regional ABB support center.