Double use of citation name

[albert-github]

Based on #8320 and doxygen/doxygen#11157 creating an assertion for builds from scratch when a citation name is used multiple times.

[afabri]

It would be good to add a duplicate entry so that we can see that it gets catched in the manual testsuite.

[albert-github]

Well that would probably be a bit problematic as it has to be in PackageDescription.txt files and we would see it every night in the overview https://cgal.geometryfactory.com/CGAL/Manual_doxygen_test/
Or are you referring to another place?

[afabri]

You added a duplicate detection feature to a script that is run to build the full documentation.
In order to test your feature we should add a duplicate, and merge this branch in integration.
If your feature works we will see it in the documentation testsuite page.
Then we can remove the duplicate again, and merge this PR in master.

[albert-github]

That would be one scenario. Another would be to do it locally, like I did for testing.
I changed the original problematic ones (#8318), i.e. the ones in

• Kinetic_space_partition/doc/Kinetic_space_partition/PackageDescription.txt
• Kinetic_surface_reconstruction/doc/Kinetic_surface_reconstruction/PackageDescription.txt

to cgal:ol-kinetic and ran the documentation generation locally so that I got the error.
In my opinion no need to create 2 extra commits (there are enough commits in CGAL already ...).