It's certainly Norvil-style, it's essentially the same, but it's more complex and fiddly-looking. In the Norvil headsteady, which I have, the split in the frame tube clamp is horizontal, not vertical, and the clamp attaches to the triangular plate on either side at one point only, with none of those intervening nuts. The one pictured above looks to me like it might be a home-brew, but I suppose more likely a knock-off. On the other hand, what do I know – maybe it's an original from way back when, or a prototype?! Pictures below are of my Norvil headsteady, bought from N*rvil up to 20 years ago.
View attachment 71268
View attachment 71269