<< the animosity between Mr. Bradbury and Mr. Alland. <<

I don't know if there was any "animosity"; Alland liked Bradbury a lot ... well, until I sent him that Bradbury-written preface! And I haven't yet read an interview where Bradbury ever said anything bad about Alland.

I betcha Bradbury simply felt a yen to write a "funny" story about the writing of IT CAME FROM O.S. and he had to make Alland and Arnold out to be vulgar buffoons in order to MAKE it funny; and by leaving out their names, he figured he was "in the clear" to do so.

He DOES really seem to think that the ideas in the two treatments are worlds apart (Alland-Arnold's ideas in the "vulgar" one and just his in the "good" one). And THERE he's stuffed full of wild blueberry muffins; they're exactly the same 'til the finale. But probably he's just mixed-up after the passage of so many years.