If you take a GRE subject test again will it average with your previous score?

[SJCHA]

Hi, I did the GRE Subject Math test on December 2006 and I am planning to take it again because I feel that I did low on the test. Today a friend that is planning to take the Physic test told me that when you take the gre general exam again your score gets averge with your previous score. I have googled trying to find if it was really true but I can find it.

So the question is, if I take the exam on Nov 2009 will my score get averaged with the previous one or the only score that will matter is the new one or the old one?

Sergio