What will you do when your boss and your boss' boss have a different opinion on tackling any particular problem, while you are the main focal person?

Different opinion are to be resolved by using conflict Management technique, you as a focal person is assumed to be either a benefactor or a looser based upon a decision which your first line manager and Second line manager reaches on post discussion between them.

The best solution will be related to WIN WIN situation for both the parties where business Ethics  in organization context are met , you morale doesn't do down and no financial losses are nil.

Hope this helps else raise a query based on the answer I have provided.