[KevinH]

I can not duplicate that at all with Sigil. And your image does not show any toc info on your new empty second title page.

My guess is you had a toc.xhtml file that was not listed in the OPF spine at all and so when you inserted a new file it rebuilt the spine and properly included it.

Since this is an epub3, is your toc.xhtml your NAV document? Or is it a user html table of contents you want people to actually see just like any other content?

What manifest properties are listed for that file in the OPF Manifest? Does it have the "nav" property? And how it that file listed in the OPF Spine? Is it linear="no"?

If after all editing is done and your have rebuilt the nav to reflect any new headings and things, if you do not want the nav to appear you can remove it from the OPF spine. But it must have the nav property set in the opf manifest on it to pass epubcheck.