A story behind these 94-96 tuvan stamps ("Tuva 2000" stamps) is rather amusing (I believe).
As you surely know USSR collapsed in 1991. I don't want to dig into politics and discuss reasons for that, just putting everyting in a chronological order. So as USSR collapsed in 1991, Russian authorities faced a tough challenge - how to keep Russia (Russian Federation) from collapsing further.
Yeltsin, a head of the country, just before (1 year before) made a huge statement - he said that every subject of Russian Federation may grab as much sovereignity as they can handle.
Surprisingly for many he kept his promise and followed this rule through early nineties. Again I don't want to dig into politics and discuss how good or bad was that decisions, whether he had other options, etc. The decision was made.
Many believe this significantly weakened central authorities powers within the country, but also prevented Russia from collapsing into number of independent countries (by making them semi-independent thus feeding appetites of those who wanted more independence). Also many believe this political strategy created Chechen-Russian conflict, which is surprisingly very much related to these Tuva stamps (I'll explain it later).
So what we had in the 1994-1996 was called as "Sovereigntly Parade" in Russia. Many federative states already had their official hymns, local governments, local parlaments, even local army (Chechen Republic), local laws and local regulations (sometimes contradicting to central authorities, for example so-called "Chechen Avizo").
And some started considering creating their own customs (guess what would happen next?) and post offices. And post offices require their own stamps right? So Chechen Republic was the first who started printing their own stamps. This was semi-legal - the story of these stamps (or "stamps", as some call them) is also interesting, but let's return to Tuva.
Since early nineties there was a group of people who recognizes a marketing potential behind the real official Tuva stamps. They certainly did not want them to be just another unrecognized/unofficial issue (as Chechen stamps were) - so it took them several years to sigh all the necessary papers with the local government of Tuva (again some people believe they have to negotiate with Russian Post instead, so these papers weren't enough to claim these stamps as actual stamps).
Finally stamps were printed and delivered to Tuva (very significant fact - please remember that). They even started to circulate - people started using them for local correspondence (another significant fact). Although some people are selling envelopes sent from Tuva to other Russian cities, these are likely fake ones. I've never seen any real envelope sent from Tuva so far.
Unfortunately for these Tuva stamps, 1995 was the year Chechen-Russian war begins, and lots of people in Kremlin, Moscow (very likely incl. Yeltsin itself), started to believe that the former strategy of "Sovereigntly Parade" became too dangerous to follow it further. And they started to cut down local authorities' rights and freedoms. No contradictory laws and regulations, no unauthorized activity (including stamps). Russian Post issued a document which explicitly banned processing a correspondence with "so-called Tuva stamps". On that basis some people claim that these stamps are "fantasies", because they weren't approved by the Moscow. I give it up to reader to decide if they are "fantasies" or not (I personally have them in my collection).
Again unfortunately the story of Tuva stamps wasn't over. Several "philatelic agencies" started to issue "Tuva stamps" furtner. You may easily find them at ebay. They never have any mentioning of "post" and issuer's name also varies - "Tuva", "Touva", "Tannu-Touva", etc. These are definitely "fantasies".
I remind you that those "Tuva 2000" stamps were printed under the Tuva local government control, were actually delivered to Tuva, were sold there, and even circulated there! Contrary to that, these recently printed "fantasies" were printed w/o any govt control, never delivered to Tuva, never sold there, never used for postage / postal charges. The only problem with "Tuva 2000" stamps is that document which explicitly bans their circulation.
Again it's up to you whether to decide what to collect. :)