3rd Biometric appointment - EB1C TSC concurrent filing

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I received my 3rd biometric appointment letter this week.

I did my 1st biometrics in June followed by 2nd one in September and another one scheduled for next week.
The major difference between the 1st and the 2nd one is the code. 1st one had a code of 3 and 2nd one had a code of 5. There is no difference between 2nd and 3rd now. Its for code 5.

I already received my EAD in August.

Anyone in this group is in similar situation? Or anyone know what could be the reason for the 3rd bio?
Please share your thoughts.