Mh, just noticed that a TOC does not work too well if several sections have the same title.
Curiously, I noticed this on the XWiki 11.5 release notes page. 
Actually, that’s the link for the “Developer’s” Miscellaneous section, according to the TOC…
Ok, I also do not have a clever idea how to work around this problem, I just wanted to ask if it’s already known and/or if maybe someone else has an idea…
Mh, thinking about it, adding a “number of occurences” to duplicate anchor names might be an option - I first thought that it would make make external links pointing to specific sections of the page too fragile, if the page is modified afterwards - but then it dawned on me that currently such links also would not work at all. The link would always point to the first occurrence of the repeated section name.
So just adding a number to it wouldn’t really make things worse, but would help the TOC. Or is it possible to provide a manual anchor ID, so disambiguation could be done manually? (And if this is possible, it might be a good idea to introduce it on the release notes page. 