With retaining walls you should avoid overlapping geogrid without following proper procedures for overlapping materials. There must be at least 3 inches of soil between geogrid layers to avoid movement between geogrid materials. With road stabilization projects you can overlap geogrid to accommodate wider roadways but only overlap 1 to 2 feet. Also, make sure the bulldozer blade avoids catching that overlap/centerline by pushing the aggregate the correct way across the overlap. This is a general answer, always determine exact requirements from a civil engineer.