I recently purchased a new workstation and installed several versions of Unreal Engine along with the Epic Games Launcher of course.
Upon starting the Launcher I noticed that I had duplicate listings of all "My Projects" in the Library Tab. Two of everything, each with the exact same path. It took a bit of searching online to find the answer. More than I expected. I assumed it would involve uninstalling and re-installing engine versions or something like that. Instead, it was a simple edit in an ini file related to settings for the Launcher app.
Here is a link to the post on the unreal forums explaining the answer. Though accurate, the title of the post is a bit misleading for the resolution to my problem but it IS the correct solution. I wasn't trying to remove an individual project from the launcher as the title suggests but solve a more global issue with the launcher's behavior. I read somewhere else that it was recommended to set the .ini file to "Read Only" in the file properties after adjusting so that it won't get re-written at some point in the future. Maybe a good idea to consider though I did not do it myself.
Thanks to user Go_Cool_Events @Appifiny_Solutions for the post.