Tiberius Julius

Here's a question for George Knysh:
I know
http://en.wikipedia.org/wiki/Tiberius_Julius_Aspurgus
is supposed to have received the name Tiberius Julius upon being made Roman citizens, but why would
http://en.wikipedia.org/wiki/Tiberius_Julius_Rhoemetalces
http://en.wikipedia.org/wiki/Tiberius_Julius_Synges
http://en.wikipedia.org/wiki/Tiberius_Julius_Mithridates
http://en.wikipedia.org/wiki/Tiberius_Julius_Ininthimeus
etc keep that name? Being a Roman citizen could hardly have enhanced their legitimacy as Bosporan rulers.
And how about this guy then
http://en.wikipedia.org/wiki/Tiberius_Julius_Alexander
or this one
http://en.wikipedia.org/wiki/Tiberius_Iulius_Abdes_Pantera ?

Is it perhaps instead a politico-religious statement that they are 'converts' to the Roman 'universal' religion?


Torsten