Hi,
I'm an IGCSE student and recently took BIOLOGY IAL and examined Unit 1 AS in Jan 2020, the result came out and I'm thinking of resitting the exam in May/June. I've already registered and payed for Unit 2 and 3 of AS and added the cash-in code and entered my UCI before the Jan 2020 results came out. Now I want to register for Unit 1 again, should I enter the cash-in code again when registering or no.