That is a good theory. I never thought of that being the reason for Voldemort wanting Ollivander - to fix his wand, or even to make him another wand. But that makes sense, because he knows that his wand won't work if he tries to duel against Harry - priori incantatum will happen. Of course, if Harry and Neville were both fighting Voldemort and Neville threw himself in front of Harry in a duel then if Voldemort's new wand is of the same core as Neville's we know that once again it won't work.