When I looked at the first source, the text had changed. Now it says, "'El Gobierno ha decidido mantener en forma indefinida un horario único en Chile cntinental e insular', dijo el secretario de Estado. De esta manera, la zona horaria permanente será GMT-3 en el continente y de GMT-5 en territorio insular." The second sentence translates, "In this way, the permanent time zone will be GMT-3 on the continent and GMT-5 in the insular territory."
The change probably represents a clarification. The phrase "horario único" could refer to the contrast between the island areas and the continent, but it could equally well refer to the contrast between the use and the non-use of daylight saving time. I think it's the latter.
Gwillim Law