That sounds quite unlikely. Of course, there are plenty of cases where a counterstamp was applied to affect the area or value of the host coin. However, in all these cases, the host was necessarily worth less than its intrinsic value (overvalued).
If the counterstamp is meant to devalue the coin, you simply export the coin to receive full value. If the counterstamp is meant to keep it in the country, it must be overvalued, or it will disappear from the country anyway.
Keep in mind that the MTT was not a foreign currency. It was the only large silver coin available and a unit of account. Taxing it would drive out the coin from circulation completely and leave the country without coins. In other words, taxing a coin in an area where the coin cannot be replaced will yield practically no tax income and cause great harm to the local economy.
Peter