You are looking for push instead of navigate. When you use navigate, it look for a route with that name, and if it exists navigate to it. When you use push, you go to a new route, adding a new navigation to the stack.
See the documentation here https://reactnavigation.org/docs/en/navigating.html#navigate-to-a-route-multiple-times
In your case, you should do:
NavigationActions.push({ routeName: 'User', params: {userId} })
or through your props (make sure your props has ‘navigation’):
this.props.navigation.push('User', {userId:'paramValue'})