Install Python2 and Python 3
To obtain Python 2.x and Python 3.x on the same machine, you need to follow the following steps.
Install Python 2.x and Python 3.x with the default windows installers.
Go to the default installation path (C:\Python3x) and rename python.exe to python3.exe.
Edit your environment variables to include the following directory link
C:\Python27\;C:\Python27\Scripts\;C:\Python34\;C:\Python34\Scripts\
The above is based on installing Python 2.7 and Python 3.4. Edit the versions based on your requirements.
Note that there can be a conflict when you change your environment variables because the two versions have the same name: python.exe.
Therefore, if you run through this error, ensure that you have followed step 2 carefully and renamed your python.exe file to python3.exe. So when the user runs python, version 2.x will get executed. With python3, the 3.x version will get executed, giving you access to both Python 2 and Python 3 on the same device.