user controls and validation

is there a way to stop one user control firing the validation on a separate user control when they are used in the same web form?
i have a user authentication page with 2 user controls - control1 (LoginControl) allows existing users to login; control2 (RegisterControl) allows new users to Register.
both controls have fields controlled by validation, however at the moment when the user fills in the login form and hits the login button on LoginControl, the required field validation on the RegisterControl is fired, and vice versa filling in the register form and clicking register fires required field validation on the LoginControl
is there a way I can have each user control only fire the validation on their own control, even if i use both controls on the same page?