Excuse me, but I believe you'll find this is a common misconception in the Quiz World.
As Attila spent his entire life surrounded by fellow Huns, it is more likely that he would be known in his community by the Hunnish equivalent of 'Sir', 'Mate' or possibly 'THE Hun', with obligatory capitals.
Conversely, with the exception of his parents, Rupert's environment appears remarkably bear-free; his peer group appears to comprise only Badgers, Dogs, Elephants, Gypsies and a small Chinese Girl. However, nowhere in the work of Mary Tourel or her Daily Express successors is he referred to as anything other than Rupert Bear, being no doubt content to stress his allegience to the ursine world rather than his sole tenancy or domination of it.
I strongly believe this question should now be put to bed, as should I.