Do only use the first year (when S01E01 was aired), not the ‘range’. Since 1998 appears in both of your folder names, Plex might mistake them as the same series.
Perform the Plex Dance after changing the folder names.
Only add the shows back separately.
Don’t download/rip directly into folders which are monitored by Plex. Always use a temporary folder until the file is complete and has the correct filename. Only then copy/move it into the destination folder.
