### Bug description

On every ePub I make in Quarto, the chapter numbers are generated automatically and then duplicated in the final output.

Here's the ePub `toc.ncx` source in a book with three chapters. Note how each `<text>` label includes two instances of the chapter number.
```xml
 </docTitle>
  <navMap>
    <navPoint id="navPoint-0">
      <navLabel>
        <text>This is a book</text>
      </navLabel>
      <content src="text/title_page.xhtml" />
    </navPoint>
    <navPoint id="navPoint-1">
      <navLabel>
        <text>1 1 Intro</text>
      </navLabel>
      <content src="text/ch001.xhtml" />
    </navPoint>
    <navPoint id="navPoint-2">
      <navLabel>
        <text>2 2 Sample Page</text>
      </navLabel>
      <content src="text/ch002.xhtml" />
    </navPoint>
    <navPoint id="navPoint-3">
      <navLabel>
        <text>3 3 Typical grid</text>
      </navLabel>
      <content src="text/ch003.xhtml" />
    </navPoint>
  </navMap>
</ncx>
```

Maybe this is by design? but I've tried setting `toc: true` to change the behavior and can't figure this out.

Here's the ePub output viewed in the Calibre ebook viewer:
![image](https://user-images.githubusercontent.com/2120747/233811876-83acd113-fb54-4f02-8181-99b4939dddc8.png)

I have a simple working example on Github: [richardsprague/quartosample](https://github.com/richardsprague/quartosample)
OSX 13, Quarto 1.3.333



### Checklist

- [X] Please include a minimal, fully reproducible example in a single .qmd file? Please provide the whole file rather than the snippet you believe is causing the issue.
- [X] Please [format your issue](https://quarto.org/bug-reports.html#formatting-make-githubs-markdown-work-for-us) so it is easier for us to read the bug report.
- [ ] Please document the RStudio IDE version you're running (if applicable), by providing the value displayed in the "About RStudio" main menu dialog?
- [X] Please document the operating system you're running. If on Linux, please provide the specific distribution.
- [X] Please provide the output of `quarto check` so we know which version of quarto and its dependencies you're running.
dragonstyle
2023-04-22T23:39:30Z
richardsprague
bug triaged-to regression epub
v1.3
closed
ePub displays duplicate chapter numbers
https://github.com/quarto-dev/quarto-cli/issues/5278