buffer_param is seen twice in these reference pages because of the constrained specialization
https://121.capy.prtest3.cppalliance.org/capy/reference/boost/capy.html
The links to specializations of a class, as well as its deduction guides, should be on the same page as the class. Not in the context of the parent because this is confusing. At the very least, this should be an option. This issue has been reported and requested multiple times by many people.