Do some more research about tangs- you'll find that a 38 gallon is too small in the long run for one tang, let alone two. There's lots of other fish that are appropriate for a 38- why choose fish that aren't?
Instead of spending money on a fish- get a couple of good marine books. It will save you trouble, money and fishes' lives in the long run- a much better investment! Robert Fenner, Scott Michael, and John Tullock all have good books for beginners.