I have two movies (two versions of the same movie) and they are “stacked” inside one file. This symbol appears on the poster.

How do I watch the version I want to watch?
I don’t want to separate the file. I want to keep it stacked, but watch the one I want to watch in the stack. I’m assuming this is why this feature exists in the first place, because otherwise why would Plex create the stack at all?