Just on people buying multiple versions of the same game ...
From what I have seen, most people can be motivated to buy a re-release of a game they already own but this typically only happens if the new version of the game is released years after the initial release; and typically only if it is released on a handheld or next generation console.
There are a handful of people who will buy multiple versions of the same game on different platforms at the same time, but this is an insignificant minority; and certainly not a good idea to build your business model around them.







