Dual cost system is a monetary policy system, also known as dual currency system. It stipulates two currencies of a country or region and their status in international trade and financial transactions. Under this system, one currency is designated as the main foreign exchange reserve currency, while another currency is used for daily transactions, payment and settlement.

The advantages of the dual-volume system include expanding international transactions and promoting economic development. By designating a currency as the main reserve currency, countries can conduct transnational transactions and capital flows more easily, thus promoting international trade and investment. The disadvantage is that the dual system needs a lot of money reserves to support it. At the same time, if the reserve currency expands or depreciates, it may reduce its international reputation and economic strength.

Historically, the two-track system has been widely used in the international financial system, such as the gold standard in Britain and the gold exchange standard in the United States. In contrast, this system is rarely used in the world today. As a monetary policy system, the dual-cost system is often used in smaller economies, or in regions and industries with large price fluctuations, such as oil and other commodities trading.