I've been looking for nearly a year now. I do see them once in a while, but they're usually sold before I can lay dibs on them.
I've had two thoughts on cloning one, though. The first would be to take the left-side style and machine the void to accept a close-fit slab of steel and silver-solder it in the valley between the two ends. The other involves fashioning a bayonet lug and likewise silver-soldering it to the gas block on the right. Done with care you could blue, park or paint and it'd be tough to see where the join was.
If I had access to a TIG, adding metal to the right gas block would be another way to get it done.