Morning Burney - you may be right but I'm not picking up on the same differences you see. What I do see are B1 near-copies fabricated in steel that have near similar characteristics. (The fin construction, for example, is identical.) I don't know why some are stamped and others aren't but a credible option is that after the film some found their way to EOD - and attracted the normal audit protocols. I've attached an image of a submunition so marked (but in pen!)I don't believe this particular model was a film prop. It makes no sense to make something like this more complicated than it needs to be. The steel insert on the nose is removable and looks less like an original than the one in your other post.
The one I have is marked 'CAR 420', I know not why.
The BoB link is interesting - particularly given the confidence of Propstore. The detachable nose piece fits in with the story that the re-usable steel body was made to contain a pyrotechnic which, when initiated, gave a cinematic impression of a incendiary functioning. Difficult to know for certain but might the dark area on the nose insert indicate discolouration through heat? If this is correct it would go a long way to explaining why the item was made in steel and why the nose detached as it does. It think Occams' razor applies - but I'm happy to hear more!
All the best. A