Issuance of tax code

If an employer, or a pension provider, has two reference numbers for an employee or pensioner, (NINO and all personal details exactly the same for both references) does this mean that HMRC need to be requested to issue a tax code notice for both reference numbers rather than just one for each NINO/ person?

Hi,
Yes if they are two separate sources of income although from the same payer ie 2 different payslips possibly?
Then each would require their own tax code to prevent any duplication of your personal allowance.
If they are paying you through just the one paylsip and the sources of income are added together and then taxed then a separate tax code would not be required.
Thank you.