agent_x - 8:39 pm on Apr 22, 2012 (gmt 0)
You can certainly get away with having 2 similar sites on the same server..so long as they are 2 completely different sites and offer something different.
What I have experienced, if you are running 2 sites that are using the same script and have the same/similar content, one of those sites will likely never see the light of day in google. You are more likely to get away with this if they are running on separate servers.
Keep in mind as well, I have not explored this in over 3 years as I keep any similar sites completely separated from each other.
I like to think AHEAD of google and anything that can be a factor will be a factor if it isn't already.
In my (somewhat limited compared to yours I imagine) experience, if you have two sites on the same server sharing the same content, you can kiss goodbye to both of them in Google. However, I suspect it now goes further after Panda, and if two sites are targetting some of the same keywords, Google will only rank one of them. What I don't know is how much effect it has on the other.