I falshed my phone like 15 times till now and I allways had this problem
I read the on some other forum about this. this is what I read, i'll try to translate:
"... the OTP IMEI is not the same as the GDFS IMEI. This happens when, in our case, there is no OTP IMEI, it is not programmed (NULL)..."
As an end user you don't need to worry about that cuz that won't affect the well functioning of the phone.
I repeat, this is what I read and I had no problems with the phone. I wait for other opinions.