The Portuguese and Brazilian monarchs had different signatures depending on the occasion. Pedro II signed "Dom Pedro 2nd" when he wrote to diplomats, politicians, etc... (this signature can be seen in the infobox of his article). When he signed documents, he did as "Emperor". That was a tradition since the times of the Portuguese monarchs, who signed "King". Isabel signed "Princess Regent", but everwhere else was simply "Isabel, Comtess d'Eu" (not the that she used the title in its original French, not in Portuguese as "Condessa d'Eu").