Day 2 & Day 8 products have separate Unique Reference Number (URN) numbers therefore you must register BOTH kits separately.
You can register either kit here using each URN:

If you fail to register both kits ie you only register one URN, you will not receive your results for both kits. Please remember to keep a note of your URN numbers as it will be needed to obtain your results.

You will need to enter details such as your URN, booking reference, name, email, DOB, phone number, address, travel details, passport number, date & time sample collected.