Icecman:
What the Calif FTB told me to do if I mailed in a hardcopy was to write DUPLICATE on top of the return (so that if they DO receive the efiled one first, then the hardcopy second, they'd know that it was a duplicate and would reject my hardcopy - or vice versa if they receive the hardcopy first, then the efiled one afterwards). Plus they told me to make sure to mail it CERTIFIED MAIL so I could track it. I ended up not having to mail a hard copy because TurboTax did efile successfully to the state and the state accepted it.
