add second bulb to cool-tube?

Does anyone make a pre-wired socket for a 6" cool-tube?

Something I could install in the other end of my existing cool-tube so it could have two bulbs going at once.

I see some that aren't pre-wired...anyone have experience with them?

edit: I'm just thinking about how much my plants would love me with both a 400w MH and 400w HPS, setting up a second cooltube is an option, but the "blend" of light wouldn;t be as good as the way in question...

Home Depot sells dual bulb 4 foot t5 fixtures for about $35. That includes the bulbs!
I added in two of those (4 bulbs total) on the sides of my reflector and the spectrum change seems to help. Plus it is alot cooler than another 400w.
The cost of the t5's and the reduced heat means you could add about 8 of the t5's for the same price.
I know that isn't what you asked but I have had good luck with this method.