Mark Hamill, an actor involved in the Star Wars film series, went to the Disney headquarters in London where apparently people have time-traveled from the 1960s. While at the offices of the company now behind Star Wars, Hamill had to check in and give his name. Which is not Mark Hamilton.
Again, the Star Wars actor was at the Disney offices, where someone couldn't get his name right. This would be an understandable situation at maybe a hair salon, but not the Disney offices. Whoever made that mistake should take a few days leave to watch all seven Star Wars films, in order to better perform their job.
Hamill seems like a chill enough guy and he wasn't insulted. Since jokingly tweeting about his office visit, Hamill has continued to be a great celebrity tweeter.