No, that's fine. You can install Strawberry Perl independently of ActivePerl. You will need to specify which Perl interpreter to use by either modifying your PATH or invoking the interpreter under its fully-qualified name.

And of course if you want you can also uninstall Strawberry when you're done with it.

If you're really concerned about messing something up by having two installs (which really is fine, but just in case you're super cautious) you can always use the thumb-drive edition of Strawberry Perl, and install it to a USB stick.