Stamps from Tuva, Tanna Tuva, Tyva or Tyba that depict cats are never real. How can i be so sure? This region was a country for about 23 years, from 1921 to 1944. At this moment Tanna Tuva is one of the federate states of Russia.
In the time that Tanna Tuva was a country, stamps were printed with animals, true, but definately not with cats.
Remarkably, the cat ‘stamps’ that I have seen have printed on them the words ‘Российская Федерация’ (romanized to Rossiyskaya Federatsiya). This is absurd, a federate state of Russia cannot print its own stamps. Only the Russion Post may do so.
So, all cat stamps from Tuva are illegal.