you have two options:
If you are installing new AmiKit XE using the installer, it will be installed to its own and separate AmiKit XE folder. It will not touch your existing AmiKit X installation.
If you are using the upgrade archive to upgrade your AmiKit X to XE, make a copy of your installed AmiKit X folder first (just in case), and then apply the upgrade archive according to included instructions. This way you keep everything what you had in your AmiKit X and upgrades everything to XE version.
Hope it helps.