Is it recommended to uninstall existing codec related software before installing?
Yes, it is highly recommended to uninstall existing codec related software (with the exception of standard Windows codecs and codecs which support formats that the software you want to install does not support) before installing. This way your system stays clean and potential problems will be avoided. Unless the installer tells you differently it is not necessary to uninstall old versions before upgrading to a newer version, if there only have been a few small changes between the old and the new version you can just install the new version on top of the old version. That should work fine, without any problems. It is no problem when you do uninstall them, but keep in mind that the uninstaller will remove your settings too. If there have been major changes the installer will automatically prompt you that you should uninstall first.