Deberían ser todos 11 no?
También estaría bien comprobar la fecha de fabricación. Sacado de XDA:
Production date is encoded in the first 3 positions (reading from left to right):
1st position defines YEAR: 0 - 2010, 1 - 2011, 2 - 2012, 3 - 2013 and so on
2rd and 3rd define MONTH: 01 - January, 02 - February, 03 - March, 04 - April, 05 - May, 06 - June, 07 - July, 08 - August, 09 - September, 10 - October, 11 - November, 12 - December
4th position defines county:
K - Korea, C - China.
For example:
211KPBF****** (last 6 digits are hidden for security reasons):
So, 211 - 2012 November (11), K - Korea.