How to restore stock firmware on sb5101?

[hijaker]

Hello: I have a fresh sb5101 with original MAC and cert. The only thing I did to it was installing Haxorware. Now I wish to remove Haxorware, restore it to stock firmware so I can use it as a subbed modem with CC. I can no longer find the original back up. I have a clean 2mb dump from a stock sb5101. But if I flash this 2mb dump, it changes the MAC to the other stock sb5101. Basically cloning the stock sb5101.

Is there a way to restore stock firmware, without changing MAC?