> if you try to install both python-numpy and python-numpy-mkl-bin, well, you have to choose. That's how Python works

It's possible to have as many Python versions as you like installed at the same time. All of the libraries and headers include the major/minor version, packages are installed in `lib/pythonX.Y` and the Python binary itself is available as `pythonX.Y`. Few distributions support this well for anything other than a single 2.x and 3.x but it's nothing to do with how Python itself works.