Normally, you install the new build of Creo Parametric and it will be installed as new software and the old build remains. This is actually a very good thing and something you want. If the new build contains a bug that affects you greatly, you can simply revert back to the older build.
Never assume a new build is better than the one you currently have installed. Sometimes a new build will fix several bugs while creating new ones. You may have a build that contains bugs but does not affect you very much and the new build fixed that bug but creates a new one that causes some bigger issues.
I always keep the previous successful build of Creo Parametric for this very purpose.
I create a Creo Parametric launch script that allows me to easily switch from one build to another just in case I have an issue.