Duplicated Title in TOC do not generate correct links with singlehtml

[Agadoul]

Describe the bug

I have a singlehtml file generated from multiple rst.

in index.rst, there is a toctree drective to include other rst file.

Those rsts files contains multiple section. I have enabled autosectionlabel but a correct link is only generated for the main section not for the other section.

For example, the html:

<ul>
<li class="toctree-l1"><a class="reference internal" href="index.html#document-1_introduction">1. Introduction</a><ul>
<li class="toctree-l2"><a class="reference internal" href="index.html#purpose">1.1. Purpose</a></li>
<li class="toctree-l2"><a class="reference internal" href="index.html#content">1.2. Content</a></li>
</ul>
</li>
<li class="toctree-l1"><a class="reference internal" href="index.html#document-2_protocols">2. Protocols</a><ul>
<li class="toctree-l2"><a class="reference internal" href="index.html#purpose">2.1. Purpose</a></li>
<li class="toctree-l2"><a class="reference internal" href="index.html#content">2.2. Content</a></li>
</ul>

#document-1_ should prefix other item as well.

so when i click on the second content object it will alway go to the first one

any idea ?
Best regards,

How to Reproduce

we need 3 rst files.

index.rst:

================================================================
A
================================================================

.. toctree::
   :maxdepth: 3
   :numbered:
   :caption: Contents:

   1_introduction
   2_protocols

1_introduction.rst

================================================================
Introduction
================================================================

A

----------------------------------------------------------------
Purpose
----------------------------------------------------------------

B

----------------------------------------------------------------
Content
----------------------------------------------------------------

C

2_protocols.rst

================================================================
Protocols
================================================================

C

----------------------------------------------------------------
Purpose
----------------------------------------------------------------

D

----------------------------------------------------------------
Content
----------------------------------------------------------------

E

Environment Information

Platform:              win32; (Windows-11-10.0.22621-SP0)
Python version:        3.12.2 (tags/v3.12.2:6abddd9, Feb  6 2024, 21:26:36) [MSC v.1937 64 bit (AMD64)])
Python implementation: CPython
Sphinx version:        8.1.3
Docutils version:      0.20.1
Jinja2 version:        3.1.3
Pygments version:      2.17.2

Sphinx extensions

'sphinx.ext.doctest',
'sphinx.ext.autodoc',
'sphinx.ext.autosummary',
'sphinx.ext.autosectionlabel',

Additional context

No response

[mgeier]

This sounds like a duplicate of #4814.

[Agadoul]

it looks very similar indeed. Any way to fix this via an extension or anything else. I can patch the html in a second phase after the generation but this is slightly ugly.