mint vertical pair (positions 48, 58) with top stamp the variety, top stamp also has "Panama" overprint split (20.9a), bottom stamp with varieties including "Panama" reading up at right (20.4), double diagonal stroke in right "N" of "Panama" (20.5), two "Panama"s close together (20.8), and misplaced entry of basic stamp (20.12), fine and scarce pair, 1990 Philatelic Foundation certificate (Scott $200 for 20b)