Multiple unknown emails associated with my iCloud account

When initiating a new iPhone 6S with the latest backup from my old iPhone 5, I got to the point of putting in the password for my purchases to be installed on the new phone. I then had to repeat this for 20 or so completely unknown email address that appeared to be associated with my iTunes account. Obviously I 'skipped' each as I didn't have the password nor did I want the content downloaded.

I've now checked my iTunes account and these unknown email addresses are not there.

I've also checked my payment source and there have been no unusual or unauthorised iTunes payments.

Does anyone know what is going on or had this happen to them?