Sui generis
A similar case that led to the use of the label "sui generis" is the relationship of New Caledonia relative to France, because the legal status of New Caledonia can aptly be said to lie somewhere between a French overseas collectivity and a sovereign nation. Although other examples of such status for other dependent or disputed territories may exist, this arrangement is unique within the French realm.
Polygenism
Polygenism was heavily criticized in the 20th century Roman Catholic Church, and especially by Pope Pius XII in the encyclical "Humani generis", on the grounds that polygenism is incompatible with the doctrine of Original Sin.