Choosing to replace or keep both versions of an software

I am upgrading Cross DJ and was wondering if I select the option to "replace" rather than keep both versions of the software, will I have to reanalyze my songs again or is all the music and data still present in the upgraded version?
I noticed after I selected keep both, both Cross DJ 3 and Cross DJ 4 icons are present in the applications folder. However, when I click on the Cross DJ 4 icon and then click on about Dross DJ in the top navigation drop down menus, the info states that version 3.4.3 is still being used.
I noticed after I selected keep both, both Cross DJ 3 and Cross DJ 4 icons are present in the applications folder. However, when I click on the Cross DJ 4 icon and then click on about Dross DJ in the top navigation drop down menus, the info states that version 3.4.3 is still being used.