onUrlChanged always listen even I cancel the subscription & dispose the webview

I noticed that whenever I click the webview for the 2nd time . onUrlChanged listen ( duplicate ) the same data .

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`final flutterWebViewPlugin = FlutterWebviewPlugin();
StreamSubscription _onUrlChanged;

@override
void initState() {
super.initState();
flutterWebViewPlugin.close();
_onUrlChanged = flutterWebViewPlugin.onUrlChanged.listen((url) {
if (mounted) {
if (url.contains(
'${EnviromentConfig.baseUrl}/?status_id=1')) {
Uri uri = Uri.parse(url);
_redirect(uri);
} else if (url.contains(
'${EnviromentConfig.baseUrl}/?status_id=0')) {
Uri uri = Uri.parse(url);
String message = uri.queryParameters['message'].replaceAll('_', ' ');
Navigator.pop(_scaffoldKey.currentContext);
final snackBar =
SnackBar(backgroundColor: Colors.red, content: Text(message));
_scaffoldKey.currentState.showSnackBar(snackBar);
}
}
});
}

@override
void dispose() {
_onUrlChanged.cancel();
flutterWebViewPlugin.dispose();
super.dispose();
}`