How to create separate libraries

I want to make one library for action movies, another for romance and so on so forth… but when I try to do this, the library just picks up ALL the movies I have and combines them. Is there a way to keep same category libraries separate from each other?

To do that you would need each type to be in a different directory and the library would have to point to that directory and not to one that contains that one and others with content.

The problem I have seen with that is that many movies overlap in that they are really two or more genera.

You could just have one big library and filter by genera based on what you want to watch.

There really is no good solution in Plex as:
Most clients only allow filtering by one genera at a time. There is no “and” and there is no “or” in most clients.
The genera, as Plex picks them up, are often screwed up. ex. There are at least two “science fiction” genera one called “Science fiction” and one called Sci-Fi.

There is really no good, reliable, way to accomplish what you want in Plex.