Answer:
The main versions of the program (for example, RFEM 5.20.xx, 5.21.xx, 5.22.xx, and so on) are always installed in parallel and can be used concurrently. If this is not desired, you can uninstall the previous versions at the end of the installation.
On the other hand, the intermediate updates (RFEM 5.20.x1, 5.20.x2, and so on) are always installed over the previous version.
The projects are imported in the case of any update, of course. Just in case, we recommend saving the personal settings in the configuration manager before uninstalling the old version.
If necessary, the user-defined settings can be imported into the configuration manager after the update.