I have the docomo version as well and it doesn't have this generic imei number with 0000. Mine looks like a regular imei number and works fine on att, even after flashing to stock yakju and aokp, the sim stays unlocked. phone was never used, but only opened to unlock the bootloader. thats about it. Lucky i guess? idk but i ordered mine from amazon.
Only thing I am pretty sure about is that Docomo branded phone with generic IMEI were at one time locked to Docomo and were "unlocked" by fdocomo app.