I forget how spoilt I am with Monzo

Although this can be annoying, it also works as a security feature. If I’m registered for Digital Secure Key on my phone, I know both that nobody else can attempt to register it and that I am the only one who can possibly generate codes for my account.

This helps reduce the possibility of fraud, as only allowing one device to be registered means you can never become an “unaware” victim of impersonation or fraud.