I have found that using a 'portable' version of Strawberry Perl is a good way to maintain separate installations on Windows. Just download one of the 'portable' zip files (e.g. strawberry-perl-22.214.171.124-portable.zip) and unzip it.
Then run the 'portableshell.bat' that is in the top-level directory. This gives a command prompt that uses the 'portable' installation of strawberry...and it seems to ignore my existing (older) installation in C:\strawberry. You just have to remember to use 'portableshell.bat' to start up your command prompt. If I recall correctly, 'portableshell.bat' just adds the 'portable' version to the beginning of your existing path.
I use this at work to share scripts with others, since I can just install this portable version on a network share.