Yeah, the real reason for dual illuminate profiles is that camera sensors can have illuminant metameric failure because a sensor is tuned to a certain illuminate (using daylight such as D50 or D55, but could be D65–depends on the sensor). The tricolor separation filters for the Bayer array may not perform the same way under daylight as they do under tungsten (in fact it's highly unlikely that they would).
So, the dual illuminate should take care of that. Aside from the spikey light sources, there's another reason one might want to create special DNG profiles and that is to modify the sensor response to certain specific colors like John Deer green, or Budweiser red or Kodak yellow (ok, less important these days :~(
However, the X-Rite solution does offer DNG profile editing...for that you would need the free DNG Profile Editor available on Adobe Labs. You can build an X-Rite profile in the Passport software then edit that profile in DPE to tune colors. It's really not hard...(only a little geeky) but the documentation is very well done (by our own Eric Chan–MadManChan).