I could be incorrect, but I thought that, at least a few years ago, that the Bower, Samyang,and Rokinon lenses were actually ALL identical, and that the names were applied based on who the distributor or the offical importer was, for various markets around the world. At one point, Roger at Lensrentals.com conmbined the names to form the brand SamyBoweRoki or somesuch name.
I agree: I have seen some 85mm lenses that look, to me, identical, and called Samyang, Bower, Vivitar Series1, and Rokinon. that was a few years back. The Manual Focus Forum was where I encountered a number of galleries and discussions about the Bower and Samyang lenses.
The photo industry has worked similarly for decades: a lens intended for one market, say SE Asia, might be called one brand; the SAME lens, imported to Europe might be one brand, and in the North American market, the same thing could be called by another "brand" or "trade name"--depite all of them having been manufactured by the same maker.