https://www.stamp-collecting-world.com/uppersilesiaplebiscite_official.html
As Roy says :
Those stamps are from Abstimmungsgebiet Oberschlesien. (Voting area Upper Silesia)
Look here for more information :
https://stamporama.com/discboard/disc_main.php?action=20&id=25033#177220
By the way: There are 20 different imprint positions :
Recently I acquired a box lot of Worldwide material, and it contained these two German stamps with unusual overprints (one is inverted and the other is printed vertically rather than horizontally). I have not been able to identify/catalogue these stamps and hopefully somebody viewing this listing might be able to help.
re: German Stamps with O.P.'s of Unknown Orign?
https://www.stamp-collecting-world.com/uppersilesiaplebiscite_official.html
re: German Stamps with O.P.'s of Unknown Orign?
As Roy says :
Those stamps are from Abstimmungsgebiet Oberschlesien. (Voting area Upper Silesia)
Look here for more information :
https://stamporama.com/discboard/disc_main.php?action=20&id=25033#177220
By the way: There are 20 different imprint positions :