Greetings XYZXYZ
This thread is hitting on sooo many good points I don't know where to begin. The 'hide the pea' Kelvin ratings of lamps designed for growers is one of my favorite pet peeves since it generates enormous profits for lamp mfg's who push their products based on a certain Kelvin being necessary to achieve optimum results when 'properly' utilized within the plant cycle.
There are several companies out of China who will paint the inside of the lamp red. Some of them won't use a phosphor mix to get the lower end red. When doing so lumen output overall falls by 50%. The Chinese have even gone so far as to develop a 1/2 red and 1/2 white/blue on a single lamp. Ludicrous. Who wants any deviation in energy and PAR from a single lamp? If the goal is PAR UV and IR levels they could do so out of a phosphor blend evenly applied on the inside of the lamp. It's just more expensive to coat the lamps that way. They truly must take us for idiots.
But for the sake of argument let's take a fresh look at China's coupled 'solution' another way. By coupling, or fusing the glass envelopes together to form a single lamp, the two ratings of 6500 and 2700 K are then advertised as the 'optimum bi-spectrum grow lamp'. What they have actually achieved under these 'combined forces' however would be 4,500 K lamp with a 45 l/w rating, as published by the mfg's own white sheets instead of an uniform application of a 12 blend phosphor whereby 85 l/w or 166.5 vel/w is achieved with the Inda-Gro lamps which probably accounts for them being a bit more expensive. I suppose that's a run on sentence.
Lastly the Chinese have given these fixtures an IP65 rating (enclosed in glass) as it's usually sold as a tunnel light where ambient air circulating over the driver will remove any heat off of the housing before it can bake the mosfets (usual failure) inside the housing. When is the last time you purposely installed any IP65 outdoor rated fixture in a 7 day 12/12 cycle grow room?
IMO unless you thoroughly enjoy dealing with China for a warranty of the failed driver which they'll ultimately tell you is not covered under their thermal management exclusion (oh you didn't remove the glass?) then just go with an Inda-Gro as they price out about the same as the China direct and if any repairs are ever needed they do them in San Diego under the warranty.
I feel better now but I better get back to work or plants will become my full time job.