Louis the XIV's Scepter

Origin
Though Louis the XIV is well known for his long rule and revitalization of the monarchy, one of the more important events that had ever taken place in his lifetime went largely unnoticed by the French population, and even more surprisingly, the royal court. Insistent on a new royal scepter (as his old one was getting terribly drab and dingy), the King of France ordered that he be made a new one.

The smith at the time, strapped for materials, decided to melt down two golden statues of Ahura Maza and Angra Mainyu, the deities of good and evil in the Zoroastrianism religion. It is known that they were stored in the royal coffers, though how they got there is unknown - it is thought that some sort of reeling and dealing was done during the Crusades. In any event, the statues were considered 'worthless' to the French government and so were melted for the scepter.

It seems that the statues had been artifact-esque, for as soon as the new scepter was presented to Louis and grabbed hold of it, an identical Louis was created, equal and equivalent to all of him save his morality. A Warehouse Agent at the time, Alexandre Dumas, neutralized the scepter before a national upheaval could start, and covered the entire incident up with the publication of his story, The Man in the Iron Mask.

Winding up in the hands of Walt Disney, it eventually inspired the film “The Jungle Book”.

Effects
Holding the scepter creates an identical clone of the user, who is just like them but effectively opposite in their moral code - the scepter will also split itself in two, one for the user and one for the clone. The twin will try to replace the original user using any means necessary.