No. All versions are independent applications. When you install PSE11 you will get the option to convert the PSE8 catalog which will save a lot of manual work.
Once you get PSE11 up and running successfully you can uninstall older versions at a later date although I have several versions on my PC and they all use the same images on the hard drive; so there is no duplication of files.
Thank you . I will follow your advice.