It does cancel it out. This is a picture of a Russo Het Cinnamon on the left and Russo het cinnamon Leucistic on the right.

http://www.cuttingedgeherp.com/nss-f.../CinnLuc08.jpg
It's incredibly hard to tell the cinny on the left is a cinny x Russo combo because Russo's are such a subtle morph, but it's down right impossible to tell that there is cinnamon in the leucy on the right.