Actually those are coins issued for provinces joining Indonesia later in the game.
If there is an inscription on the edge, KEPULAUAN RIAU, it's Riau Archipelago coinage, issued late 1963 (even though they bear the date 1962), recalled 1964.
If there's no inscription on the edge, it would be an issue for Irian Barat, formerly Netherlands New Guinea, made in 1964 (with the date of 1962) and recalled in 1971.
Even though the catalog value of these coins is not very high I've noticed they are quite popular on
ebay, so counterfeiting is possible, especially with any irregularities or "errors".