Det här låter som Om på vinternatt en resenär av Italo Calvino.
Det var inte säkert om det kvalificerades som SF & F, men det nämns på isfdb .
Här är wikipedias synopsis ("resenär" i USA)
If on a winter's night a traveler (Italian: Se una notte d'inverno un viaggiatore) is a 1979 novel by the Italian postmodernist writer Italo Calvino. The narrative, in the form of a frame story, is about the reader trying to read a book called If on a winter's night a traveler. Each chapter is divided into two sections. The first section of each chapter is in second person, and describes the process the reader goes through to attempt to read the next chapter of the book he is reading. The second half is the first part of a new book that the reader ("you") finds. The second half is always about something different from the previous ones and the ending is never explained. The book was published in an English translation by William Weaver in 1981.
Böckerna börjar med det som förefaller vara Om på vinternatt en resenär , men kapitel 2 fortsätter i den andra personen.
...Wait a minute! Look at the page number. Damn! From page 32 you've gone back to page 17! What you thought was a stylistic subtlety on the author's part is simply a printer's mistake: they have inserted the same pages twice.
Du byter boken för en annan kopia.
Then from the very first page you realize that the novel you are holding has nothing to do with the one you were reading yesterday.