I thought ePub split had a feature where you could open each section to see what it had. I uninstalled the plugin or I would check.
You could always open the Epub in Edit Book and delete the unwanted sections. I know if you double-click on the section in the left side panel it brings up the HTML for it in the middle with the preview panel on the right. May take longer than with ePub split, but you'd have control over what ended up in the book(s).
Dear Author just had a tutorial on using ePub split the other day
http://dearauthor.com/ebooks/using-e...tion-box-sets/