Most of the yellow giganteas will be brown when they color up. I have heard some say that the yellows are bleached greens, but when you add brown zooxanthellae to yellow, you don't get green, you get a dark yellow (aka brown).
I didn't have a haddoni for about 7 years before I gave it away that was yellow and was not bleached. I haven't seen one since though. I don't think I have any pics, sorry.