One copy of Spider-Man 2 was purchased to check its quality - and another was immediately produced by one of the traders to take its place on the blanket.
This workaround relies on the fact that Microsoft is currently offering, for a time limited period, free upgrades for the Media Center add-on, and it is this process that is flawed because Microsoft does not check the validity of the original key used to activate the copy of Windows 8 Pro before dishing out another key.