Cuba: 2-Currency System
Cuba is a country with one political party and two currencies. There are CUCs, or convertible pesos, mainly for tourists and the wealthy. And there are Cuban pesos, which is what almost all Cubans are paid in — and what they use daily.
This creates kind of a strange divide between a CUC economy and a pesos economy. Technically, anyone can use both, but currency exchanges are rare and expensive for most Cubans — which is a problem, since some higher-end places only accept CUCs — and because they often buy you a better quality product. At the same time, a lot of things are overpriced when sold in CUCs, so buying in pesos is less expensive.