The answer to that question depends on how you interpret it and it may not relate to the number mentioned by OP.
North-American collectors use the Scott catalogue. From the many threads, it lists certain revenue stamps. From some threads I wonder whether it lists bogus stamps from states on the Persian Gulf. You should question any such stamp showing Christian paintings and paintings of female nudes or even of humans other than the sovereign. These are Muslim countries. These depictions are strictly taboo for Muslims.
Do you consider a to-pay label a postage stamp?
I am not sure whether it lists railway stamps and local issues. Many British isles have issued private stamps prepaying carriage from the island to the nearest on-shore post office or postbox. Railway stamps had a somewhat similar use. In 1880, the UK passed a law that made it possible to use revenue stamps for postage and postage stamps could be used for revenue purposes.
To complicate matters further, there is the question of non-recognised countries. Recently, we had a post about a stamp from Transnistria. This is part of the former Soviet Union Republic of Moldova. Seperatists, with the help of the Russian government, declared Transnistria independent. Its post office issued stamps that can be used internally, and probably on mail to Russia. The UPU and most countries do not recognise these stamps as valid postage stamps. Yet, it has been issued by the official Post Office - according to some - of Transnistria.
Lately, countries issued stamps with two-dimensional barcodes. Each stamp has a unique barcode. The stamps are printed in millions. Tecnically, there are as many different stamps as there are stamps printed.
Below are some recent 'different' stamps. The first, as can be seen by the D1 and W1 are printed by two different printers. The two on the right in the second picture are from different cylinders. There are many Victorian stamps printed from multiple plates that have the plate number incorporated in the design. So, if you consider the Penny Blacks and Penny Red (stars) as not-different, those with plate numbers in the design are different. The third is a modern version of stamps that have an issue date in the design. Here the printing year is in a code printed in iridescent ink. Spain did something similar for another reason in the 1800s.
My guess would be that - even adding issued by the official post office - every answer to your question can be different and all correct.
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