3 Mark German Reich with three line typography overprint "Plebiscite / Olsztyn / Allenstein", variety "double overprint" along with Michel-no. 20 on postage exceeding tariff rate registered cover from "old Ukta 24.8.20" to Hanover with on the back arrival stamp from 26.8.20, photo expertize Wasels BPP (2019) : "overfranked, genuine and immaculate. ", the double overprint the Michel-no. 14 is very rare, Existing postage exceeding tariff rate copy accordingly of prime rarity and perhaps one of the few possibilities ever these stamp on cover to acquire!