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John Doubleday (about 1798 – 25 January 1856) was a British craftsperson, restorer, and dealer in antiquities who was employed by the British Museum for the last 20 years of his life. He undertook several duties for the museum, not least as a witness in criminal trials, but was primarily their specialist restorer, perhaps the first person to hold the position. He is best known for his 1845 restoration of the severely-damaged Roman Portland Vase, an accomplishment that places him at the forefront of his profession at the time.
While at the British Museum, Doubleday also dealt in copies of coins, medals, and ancient seals. His casts in coloured sulphur and in white metal of works in both national and private collections, allowed smaller collections to hold copies at a fraction of the price that the originals would command. Thousands of his copies entered the collections of institutions and individuals. Yet the accuracy he achieved led to confusion with the originals; after his death he was labelled a forger, but with the caveat that "[w]hether he did copies with the intention of deceiving collectors or not is open to doubt".Little is known about Doubleday's upbringing or personal life. Several sources describe him as an American, including the 1851 United Kingdom census, which records him as a New York-born British subject. An obituary noted that he worked at a printer's shop for more than 20 years during his youth, which gave him the experience of casting type that he would employ in his later career as a copyist. Doubleday's early life, family, and education are otherwise unknown. He died in 1856, leaving a wife and five daughters, all English; the eldest child was born around 1833.

answer the following question:

What is the full name of the person who dealt in copies of coins, medals, and ancient seals? 

John Doubleday