IMO the normal looking sib almost looks like a Het russo. I had the opportunity to see a Het russo in person over the weekend at a show and Mark from MBReptiles showed me his Het Russos and helped explain the differences from normals.
That normal sibling has all of the same markings, the high white, the very light coloration and the reduced pattern.
Just thought I would throw that out there....
Good luck figuring out this genetic mystery.
EDIT: Pic for reference.... http://www.cuttingedgeherp.com/nss-f...cSNormal05.jpg