Plex is recognizing the files as two versions of the same episode, not as an episode split across multiple files.
This is most likely because your file naming does not follow Plex recommendations, and Plex is very picky with TV show naming and organization.
As noted in the documentation, not all Plex clients support movies/shows split across multiple files. You will be much better served by combining the two files.
You can use MKVToolNix to combine the files. The output will be a MKV file, but the video and audio streams will not be altered.
See [HowTo]: joining multi-part movies files with MKVtoolnix GUI for details on combining files.
Edit: There is probably a GUI tool for combining multiple mp4/m4v files, but I’m not aware of one. You can use FFMPEG if you are comfortable with CLI.
If you want to keep the separate parts, rename them according to Plex’s recommendations.
For example:
/TV Shows/Cosmos/Season 01/Cosmos - s01e02 - part1.m4v
/TV Shows/Cosmos/Season 01/Cosmos - s01e02 - part2.m4v
After renaming the files, Plex Dance the entire show. This will clear the incorrect information from the Plex Media Server database.
You can test before renaming all episodes.
- Rename one episode according to Plex recommendations.
- Follow Plex Dance steps 1 - 4 as listed
- For Step 5, return only the renamed episode, not the entire show.
- Step 6 as listed.
- If it works as desired, rename the remaining episodes and add them to the library.
