I DO believe it does exist !
Just rightclick on each trunked, conventionals and select Check for Duplicates.
Then click the checkbox for any you want to delete and then select Apply. It will delete from conventionals you'll find right away.
On the trunked to see them disappear select another system or so then return and they wont show n - A bug.
Far as global I go to Scanlist listing tab and sort em by alpha or frequency by clicking on the column labels.