How to install and run multiple versions on a single Windows box?

To install the first splunk on Windows, just download and run the msi file of version you choose.

To make second installation, follow this procedure:

 a. In a cmd console, cd to the splunk home directory, usually in: program files\splunk
 b. run: bin\splunk stop. 
 c. run: bin\splunk disable boot-start. 
 d. cd ..
 e. move the splunk folder to another location you choose.
 f. install a new splunk version by download the corresponding msi file (Windows service will be added automatically).
 g. now the new splunk can start as windows services or with the command: splunk start
 h. The old (moved) splunk can be started from two command windows with --nodaemon, i.e.,
      In the first cmd window, run: splunk start splunkd --nodaemon
      In the second cmd window, run: splunk start splunkweb --nodaemon