"Cash-in" question

Here's my situation, i did an AS maths exam (c1, c2 and s1) in january as a private candidate but on the entry form i didn't ask for the grades to be cashed in once i had completed them because i was going to carry on the a level at the same centre. But after i got the scores for that session, i found another centre that offered it cheaper (to sit an exam) so i completed my a2 (c3, c4 and m1) in this centre.
How would i cash in the grades because if i cash them in at the second centre will they have the record of me sitting my as modules in the other centre, im confused.