On January 25, 2022, Colombia issued the stamps identical to those released on December 20, 2021 by Mexico to celebrate 200 years of relationship (1821-2021). This joint issue, first reported by Don Birschel (USA), became actually a concerted issue [C] for which not all information is available. Both countries issued a se-tenant pair of symmetrical design stamps showing the figure “200” and a stylized butterfly with the colors of the countries’ flags. While Mexico announced the issue of 50,000 pairs of stamps in panes of 25, the stamps of Colombia apparently produced in panes (size unknown) at 14,000 samples (probably 7,000 pairs), have been seen already in souvenir sheets of [1px2] and [1px3], but also in blocs of [2px2]. The Mexico stamp is self-adhesive. Additional information is needed here, but the catalogue (Volume 14) has already been updated with these first data.
Joint Stamp Issues 
Three weeks separated by a year. About as close to a true joint issue as there is. Close but no cigar. Several joint issues were not issued on the exact same day. What IS the criteria?
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A twin issue [T] corresponds to a joint issue with stamps released within less than a week. Actually same day is ideal for a [T]. Beyond 7 days, it will be called Concerted [C], but remains a true joint issue as long as designs are the same. For details, see Catalogue Vol 1 page 13.
https://fr.calameo.com/read/006555730d6fa369aeca8 RZ
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