A bug is causing the Windows 10 KB4494441 May 2019 Cumulative Update to be shown as being installed twice on some computers according to Microsoft and user reports. When users see the update listed twice, it is nothing to worry about and Microsoft is aware of the issue. Microsoft has stated that they are working on a fix so that this type of issue does not happen. Users should not try to uninstall this update, even if its listed twice as it includes numerous bug fixes and security updates.
Source: https://www.bleepingcomputer.com/news/microsoft/windows-10-kb4494441-update-may-be-shown-as-installed-twice/