I'm new to BB developing, but I'll give it a shot
Does your class extend Screen or a subclass of it? If so, then it already implements TrackwheelListener. (see the HelloWorld example) It seems to me that you trigger both your custom TrackwheelListener and the standard TrackwheelListener. So, a matter of proper overriding will keep the standard one from appearing to my opinion.
Let us know if it helped you.
Best regards, L J.