For most lamp makers except Eye-the lamp makers get their halide salt mixes from Anderson Physics labs.Also HPS lamp amalgams.Dr Anderson is the Physicist that came up with the formulas for the halide salts and HPS lamp amalgams.
One thing is, who is manufacturing them, the other question is, who is designing the composition.
Many these suppliers deliver the composition on a custom order, without exactly knowing why the composition is to be like that. So when some composition (or the mix itself) leaks out to some shady lamp makers who try to copy the lamp, they usually fail because many details are still hidden from them.
Of course, the get some of the info from the lamp developers when they are fine tuning the composition, but generally it is lamp makers "know how".