You assume wrong. Upgrades are upgrades and selling such a version must include all previous versions lleading up to the current one. Anyway, Cs2 is so old, nobody cares..
I thought that might be the case. So, unlike my two separate Autocad purchases,both full version and not upgrades, I can't sell or give one away without losing both? Hmm, anyway, it's not so old to be unusable for architects and engineers.