When you purchase Adobe Lightroom from Mac App Store, you can find two identical versions of Adobe Lightroom installed on your Mac. This can happen due to one of the following reasons:
You’re viewing help for Photoshop Lightroom.
Not your version? View help for Photoshop Lightroom Classic.
All of your photos are stored in the cloud and both versions of Lightroom app uses the same library, so your photos are safe.
Since both the versions access the same cloud-based library, you can use both the versions. However, it is not recommended.
You should keep the version installed from the store where you purchased the app. This way, you are assured that the app will be updated consistently.
You can identify the version from the installation path of Lightroom on your system: