already defines a member called 'OnNavigatedTo'

It sounds like you have at least two definitions of the OnNavigatedTo method.

You can only do this if the number and/or types of the parameters for each 'overload' of the method are different which I suspect won't be the case here - there will just be a single NavigationEventArgs parameter for them all.

So, you need to remove the superfluous definition(s) so you only have one left and (if necessary) find a way to combine the code you had in each method previously.