I used to grow with 250-watt lights. I had one 250-watt MH for veg and two 250-watt HPS for flower. They were low budget lights with simple batwing reflective hoods.
　
As an experiment I screwed the hoods together along their edges, I drilled two small holes through the front and rear corners of each and used sheet metal screws to connect them and created one large well curved hood with an HPS bulb on both sides and a MH in the center.
Actually my first attempt was to just combine one MH and one HPS but later I altered that and came up with the triple light setup.
　
I grew in a closet but I had adequate ventilation so the highest my temperatures ever reached, that I saw, was 82 degrees and normally stayed around 78 to 80 degrees.
　
My plants responded very well to the combination of both MH and HPS light spectrums.
　
Since switching to a 400-watt light I did at times add one of the 250-watt lights if I wanted to add an additional light spectrum to the MH or HPS I was running in my 400-watt light at the time.
Of course I did not attach them together since with having different designed/shaped hoods the same sort of alteration could not be made but I would hang them side by side and every few days move my plants so they would then be more under one light than the other.
　
Something else that can be done if someone has multiple lower wattage lights like 250-watt lights and a simple batwing reflector is to remount the socket unit to one side and then add another socket unit from another lamp to the other side (side, not end) and have two bulbs under one hood. Again mixing the different light spectrums, MH and HPS, does make plants happy.
　
If someone can deal with the temperatures and has the needed design equipment it is very simple to do and well worth the little time and little effort needed to do it.
just cause there not dying doesnt mean there do the best they could be..