Too the best of my knowledge... no.
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1) First, its not in the habit of Stardock to leave old version of games lying around. You might get the odd pairing of versions where you could download the release version, and download a pre-release version (often called betas). To switch the views of the different versions, set the option in Impulse to download the pre-release version of programs. However, thats not what you're looking for...
2) The second problem is that Sins was in beta back when "Stardock Central" was still in use. Impulse was intended to be released with Sins, but thats another story. Impulse was in beta back then along with Sins, so any Impulse archives that exist from that time might not work too well.
3) The third problem is finding someone who has a "SDC installer" from back then (as its no longer available to download from Stardock to the best of my knowledge). You could probally get the archives you seek from them too. Then you have to figure out how you would get the data from the people who have them. Ofcourse, there is the slight problem of weather or not Stardock and Ironclad would be happy with you trying to play the original betas. Also, I don't know if its legal to do what I suggested here.
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You're best bet is to go contact either Stardock or Ironclad to see if you can access those old betas. Here are some e-mail addresses you could use:
support@stardock.com
support@ironcladgames.com
However, I seriously doupt that will work (I don't see much reason why they would go through the trouble do so), so you may be stuck with whatever information you can gleem from these forums.
