The Russians counterfeiting ducats was simply a matter of expedience. The coins were of full content, and widely accepted. Much more so than a Russian 5 Rouble at the time or they would hardly have bothered with denigerating themselves to strike coins in the name of some other country.
With the reputation that NGC has - wouldn't you ? The Russians weren't trying to do anything to the Dutch. The Russians merely needed a form of money that was accepted anywhere by anyone - because Russian money was not accepted anywhere and by everyone. The Dutch ducat was that form of money. The Dutch ducat was the most widely accepted and most trusted coin in the world. That's why the counterfeits were only used to pay foreign debts and to pay troops in the far flung reaches of the Russian Empire. Those troops needed money they could spend, money that the people of the area or country would accept because they would not accept Russian money except at a discount.
Right, the Russian ruble had a series of devaluations from the 19th century and into the 19th century. Any money that has been devalued doesn't exactly attract wide usage - and in fact - people will avoid taking it. In a similar vain the Russians, British, French were striking the Austrian Maria Theresa thaler of 1780 well into the 20th century as it was used in the Middle East. I know for a fact they were still being used in Yemen for certain transactions late in the 20th century - people I know with a petroleum company remembered seeing the coins in markets. Another coin the Russians made for trade was the "Bulgarian" 4 ducats in the late 19th century and early 20th century. These latter coins are now quite rare, and usually have a hole in them.