Orange River Colony 1902 Overprints Tunisian Archive Specimens

1902 4d on 6d on 6d blue, 6d on 6d blue & 1/- on 5/- (SG 136, 137 & 138). F/M examples each handstamped "SPECIMEN" type TUN1 in black (by the Tunisian Post Office as the Receiving Authority applying the handstamp to their distribution from the UPU). Interesting pieces proving distribution of these overprinted issues through the UPU. A scarce trio. See additional image below.