Us types who be immersed in this esoterica have a theory. The head may be a leftover from CURSE OF FRANKENSTEIN, the crow-eaten head Cushing cuts off the hanged man then pops into the acid. You never see it in the US or UK print; Asian print, who knows? Plop a new wig on it and Presto, instant horror shot.

My further elaboration: since it takes time (=money) to dress a dummy up in clothes which match an actor, there was an intent to use this in the film, most probably as the post-staking version of Harker after Cushing releases his soul. Whether or not Fisher actually shot this action, again, who knows. Since there's no stake visible here, I'm assuming the photo was taken before any action was filmed (otherwise there'd be blood all over the place.)

There are a couple of reasons to have used the sequence, and a couple reasons not to. First, it's a horror movie, and seeing a nice guy turn into this is pretty horrible. Second, it follows the destruction of the Vampire Woman in the previous reel, and outdoes even that for revulsion. And third, it then sets up (even better than in the movie) the old reverse-surprise of revealing the staked Lucy much later, who is gorgeous and at peace, unlike what we expect to see.

But it makes no logical/vampiric sense for Harker to be all rotten; the Vampire Woman, sure, she's been hanging around for a century, but Harker's only been UnDead a couple weeks at best. Second, it's essentially the same gag as Harker staking her; it's dramatically redundant.