Just grab a National Geographic at whip something up (this, the beginning of an article on restoring important historical documents):
Two Monarchs, a Thousand Years Apart, signed the same document.
King John, in 1215, signed the Magna Carta to preserve his Crown. Having lost the Battle of Runnymead and nearly his life, he was left with little choice. Queen Alice, in 2215, his great-to-the-twenty-eighth grand-daughter, intended to sign a proclamation noting the importance of the Magna Carta to free people everywhere and to open a new wing of the British Museum built to house this, the genesis of limited government.
The schedule called for Queen Alice to herself carry the newly restored Magna Carta - the only original copy to have survived the Third World War - to the new case. The Prince of Wales, himself nearly seventy-five, handed her the wrong document and, before a librarian could stop her, she signed directly below King John’s painstakingly restored signature.
After five minutes of on-air panic, the Queen - three days short of her one hundredth birthday - pushed her way out of the crowd of archivist and approached the microphone.
“I understand I have signed the original Magna Carta by accident and have caused a great deal of trouble. But the librarians have assured me that this terrible mistake on my part can be corrected.” The archivists knew that the same nano-technology that was used to strip out a thousand years of soot and fallout could be used to erase her mistake. With a smile on her face, but her gazed fixed on Sir John Smith (who was shortly indicted of exortion), her fifth Prime Minister in as many months, she continued. “I note, however, that since my government is apparently as honest as a Turkish rug merchant, I will ask them to erase King John’s signature as well, so I can dissolve Parliament once and for all.”