I read a book once where what you describe happened with regular reading. A popular author unwittingly plagiarized another author that he had read years before. This story may have been in Einstein Factor by Win Wenger.
I would say that there is some danger of it happening whether you Photoread or not.
How does the saying go? "Steal from one source, it's called plagiarism. Steal from many sources, it's called research."
I think it would be interesting to try it and see what happens. Maybe your work will turn out influenced by those other sources, but still be completely your own. You can always go back and activate what you've PR'd after you've completed your masterpiece but before you put it out into the world.
