Is there any way to tell if a double grille engine lid is original or does that even matter? The grille mesh material on my double grille is the same as the factory single grille and the additional grille piece is welded to the frame.

Everything Matters .... how much it matters to you, is the Qusetion...
https://pbase.com/9146gt/gt_engine_lid_with_more_ventilation

Most likely one of these:
http://www.914world.com/bbs2/index.php?showtopic=5620