I know, I tried everything. Once I upgrade one copy, the other one won't work. I even tried putting it on a flash drive, to no avail.
You have not try everything... Try PlayOnLinux ... these little piece of software use wine... but each install use it own prefix with own registry... so, your game grow from around 50 mb on the hard drive... the funny thing is that with sins in windowed mode, you can run 1.05 in the SAME time that 1.16 in a other windows and Entrenchment in one more windows...
Since a few month, problem with online game was resolved... you only need windows use impulse for the upgrade but the guy are working on it... problem is the BITS part... no sure that the old stardock central ( sdc.stardock.com/sdcentral_setup.exe ) is always functional for the last upgrade but it was working perfectly on Linux...
So, in short, wrote "I tried everything with windows OS" 