Yes, it's a very good idea to clean this up. The official name of the plugin on the Add-ons page is "Shockwave Flash" because back in the day, Shockwave was a hot format and Flash was the newcomer. Times change, and for some reason Adobe hasn't gotten around to cleaning up the inconsistencies. Normally Adobe's installer will remove old versions, but if they are considered to be "in use" they will linger beyond their shelf life. Because the plugins are stored outside of your Firefox profile folder (under C:\Windows, normally), Firefox does not offer a Remove button. You won't see a Remove button for any add-on installed in a shared location. In order to clean up the multiple files, you have two options: (1) Official method: full uninstall/reinstall. Adobe has an uninstaller for this purpose: https://helpx.adobe.com/flash-player/kb/uninstall-flash-player-windows.html Then reinstall the latest version. (2) Unofficial method: delete the old files by hand. If you type or paste '''about:plugins''' in the address bar and press Enter or Return to load that page, it lists the full path to each Flash plugin file. On 64-bit Windows, that's usually C:\Windows\SysWOW64\Macromed\Flash It's usually safe to find and remove the specific files listed on about:plugins (keeping just the latest one). Since the folder stores files used by other applications, please be very surgical in your deletions. Because that's a protected folder, you might encounter some resistance from Windows, in which case, it might be easier to use the official method.