Remove the dash after Games and add the year for each movie. Change the folder and file names. That will help Plex differentiate between the two movies.
If using the new movie scanner, you can also add the IMDB ID to the folder and file name (see support document linked below).
Plex Dance the files after changing the names.
If Plex still combines them, you can use Split Apart and Fix Match to fix things.
This works on my system:
The Hunger Games Mockingjay - Part 1 (2014)/The Hunger Games Mockingjay - Part 1 (2014).mkv
The Hunger Games Mockingjay - Part 2 (2015)/The Hunger Games Mockingjay - Part 2 (2015).mkv
With the IMDB ID:
The Hunger Games Mockingjay - Part 1 (2014) {imdb-tt1951265}/The Hunger Games Mockingjay - Part 1 (2014) {imdb-tt1951265}.mkv
The Hunger Games Mockingjay - Part 2 (2015) {imdb-tt1951266}/The Hunger Games Mockingjay - Part 2 (2015) {imdb-tt1951266}.mkv
https://support.plex.tv/articles/naming-and-organizing-your-movie-media-files/
