As an art historian, Shearer posited that
many of Marcel Duchamp's supposedly "readymade" works of art were actually created by Duchamp.

this is the link to the Shearer's paper I mentioned in the talk.

I also just know about it from wiki while preparing for the talk.
But this paper surely has no impact and has not been influential,
despite the one who write it has an interesting background,
including the checkyourfacts.org website etc,
that aimed at dispersing hoax!