No. If you use the same email address for StadtRAD and hvv switch, your existing StadtRAD membership will be automatically recognized upon activation. You will not be charged the annual fee twice.
Please check before activation to make sure the same email address is on file for both accounts. If not, update the email address in your StadtRAD account: StadtRAD Hamburg app > Profile > Personal Information > Email.
Important: The email address in the hvv switch app cannot be changed. It is therefore not possible to link it to an existing StadtRAD account at a later time.