i'm not sure if they are from the same parents. the zoo i got them from had them all together in one large enclosure. i picked two that looked slightly different in age and in color...im hoping i got a mating pair we'll see.
The first link is just a retailer that has a good description of the TRex updated bulb. The second link is a fantastic link that I am slowly wrapping my brain around. There are a couple that tested well that may be of help in large settings...however if you have year round access to the real thing you probably do not need to sweat it as much as those of us who have decided to call the midwest home...brrrr! I would love to find a combo we could use we have three different bulbs over Calvin's little 3'x2' home.
A side note, for anyone with a screen lid (ie. reptarium users etc) the screen filters up to 50% of the uva/uvb light.