Kutv.com has an article
describing a hoax perpetrated by Andy Warhol back in 1967. He had been asked to do a speaking tour at various colleges, but decided, at the last minute, that he didn't want to do it. So he sent someone else, Allen Midgette, who pretended to be him: "Midgette whitened his hair and face and adopted a Warhol persona, and, accompanied by Morrissey, went on tour. And most believed the forged artist was authentic."
People finally figured out that Midgette was not Warhol when they compared photos of the two men. Apparently the stunt was not an attempt to make any kind of artistic statement. Warhol just really didn't like public speaking. His friends say that he had undiagnosed Asperger syndrome.
Sending an impostor to an interview or lecture is a fairly common prank. Joey Skaggs
has done it often. Though I don't think this type of prank has ever been given a name. Maybe it could be called the Impostor Interviewee Prank. Or the Substitute Speaker Prank. Or just the Impostor Prank. Or what about, the Official or Authorized Impostor Prank.
I have no idea what the earliest example of this kind of prank would be. Sounds like a good research project to waste some time on!