The app is called mint4win and I know Ubuntu has a similar app called Wubi that will install Ubuntu as an application running in Windows. I've never heard of anyone running both Mint and Ubuntu inside Windows at the same time. I don't know if it's possible, and if it is, would Ubuntu Grub set up the proper boot menu?
Your safest and probably easiest route is to install Ubuntu Studio in dual boot with Windows then install Mint to make it a triple boot. I've done this and it's relatively simple. I suggest installing Mint last because the Grub boot menu in Mint is so much easier to look at than the Ubuntu boot menu.
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