Upvote:3
The Indonesians did this in several parts of the country where people were used to "stronger" foreign currencies. For instance, in parts of Borneo that had formerly used British-Malayan currency, the Indonesians issued the Riau rupiah that was pegged to the U.S. dollar, and therefore a stronger currency than the Indonesian rupiah that was not so pegged. The West Irian Rupiah was indirectly pegged to the Dutch currency.
This was a transition mechanism to get people of these outlying regions used to trading Indonesian-like "rupiahs" that had "temporary" (for some years) protection against the devaluation of the "real" rupiah. Such protections were withdrawn in 1973, a good time to do so, when high oil prices helped support the Indonesian rupiah. That put the people of these territories on an equal footing with other Indonesians.