I heard the same thing as Lurchccd stated about them. I guess a dual 20K/20K bulb for example would double lamp life with each arc tube only running half the time ... other than that, I cant see why the combo with two of the same K arc tubes would make any sense. But if they are actually just generic quality Chinese made lamps, 100 bucks for double the lamp life isnt a very good deal. Personally, I think there are a few "brand name" chinese made halides on the market that arent any better in quality than the 30 dollar Plusrite halides that can be found on ebay and on the internet. Im not trying to make a blanket statement about all chinese made halides, just that if these are an example of two cheap halides in one envelope, the 100 dollar price tag for double lamp life isnt a good deal anyway.
One issue I see with the lamps with two different colors ... short cycling halides shortens bulb life. So if one was going to cycle them on and off to alternate color every few hours, it's not good for the lamp in terms of lifespan.
But it's an interesting concept anyway.