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Yes.
Presume I have something you'd very much like to buy from me. I can add a layer to the transaction where you can only pay for it using my special monopoly money. I have now created a demand not only for my desirable product, but also for my otherwise useless bits of paper.
In the case of Russia this increased demand for their currency helps all the other holders of that currency too. Their money will now go that little bit further when they need to go shopping from neutral countries like China.
What's the reason for insisting on Roubles for payment? Is it to keep demand for the currency high?