Not that I'm aware of.
There is functionality built around the Series-Season-Episode concept in MC, in that some other fields like the [TheTVDB Series ID] or any custom fields can be set as relational to the [Series] field. I think that functionality would get broken if you tried to enter two values into the Series field. Also, the Series field is a String, and not a List type field, and you can't change that. So whatever you put into the [Series] tag will be considered as one Series name.
I have thought a little about for example Marvel movies, and the Series they may belong to, such as X-Men. My conclusion so far is that the films belong to the X-Men series, and if I wanted to group all Marvel movies together I would add a Keyword of "Marvel" to the files. Actually, in the case of Marvel movies, almost all the descriptions already include the word, and I can just search for "Marvel" in any view and it is filtered down to just those movies.