Elvis Presley and The Beatles hold the crown for the most-forged celebrity signatures of 2012, making less than half of their autographs sold certified as genuine, U.S. memorabilia authenticators PSA/DNA said Thursday.

The iconic music figures topped the list two years ago as well, when it was first released, according to BBC News.

Also on the list for most-forged celebrity signatures is former U.S. President John F. Kennedy, legendary pop artist Michael Jackson, and American astronaut and first man on the moon Neil Armstrong, the later of which came in as No. 3 on the list. The astronaut died in July and the number of his forged signatures rose dramatically after his passing.

Forgeries of Armstrong's signature also rose because he rarely signed autographs during his life.

"Armstrong is someone who is very conscious of the value of his own autograph," Joe Orlando, president of Newport Beach-based PSA/DNA, said. "Even before he passed away he was very tough to get...It really heightens the level of his market."

One reason for fake signatures in the market is secretaries and assistants of celebrities trying to respond to large volumes of fan mail. Sometimes well-known figures would have others sign photos and letters to give out to fans to speed up the process. However, official documents such as signed contracts and checks can be used as reliable sources to verify whether an autograph is authentic or forged, which can tremendously alter the value of the signature down to the smallest details like which way the letters slope and additional wording.

Beatles signatures, particularly a set of all four, is rare but autographs from the bands early years when they were together more often is more common, and therefore lower on a scale of value for collectors.

"Between 1967 and 1970 they were hardly ever together, so unless you were in their inner circle, there is no way you would get their signatures," Stephanie Connell, director of entertainments memorabilia at Bonhams in London, told Reuters.