Lot 80304 – 1920 2 1/2pfg mint single with the inverted overprint variety and right stamp showing rare broken “e” or “Sarrc” variety

1920 2 1/2pfg mint single with the inverted overprint variety and right stamp showing rare broken “e” or “Sarrc” variety, doubly signed by Dr.Dub, a top rarity of Saar, only 3 known (2 mint and one used, this the only pair), cert. Burger (2004); ex Katz.