Among those who argued for the single author theory the Shadeans believed that Shade had "faked" his death and wrote the commentary as a character he invented (Kinbote) and the Kinboteans said Shade was the invention, Kinbote the only author.

It was to these ideas that Nabokov was making the comments you refer to.

Dear Carolyn,

 

Yes, it did occur to me, even as I wrote, that your theory was not the same as the one(s) that VN was dismissing. You are quite justified in insisting on this distinction.

 

Best wishes,

 

Anthony