It's normal (and your choice) to keep the old app when you install the new version. This lets you try it out at your leisure, and go back instantly if there is a problem. Where there is time sensitive work to do, just upgrading to the new version and deleting the old could be seen as unwise. Each app version has its own set up updates. So for example if you have 19.0 and 20.0, there might be updates to 19.0.1 and 20.1.3 both available.