There is no rules support that I can see for the idea that the Hobgoblin gets to make two saves against a single effect at any point in time.Hobgoblin: Can do his stuff and when his fist save failed or he needs to make two saves, he can make another save.. If the effect is ignored after the first save, the hobgoblin doesnt need to make an save now..
The Hobgoblin's power is an Immediate Reaction to suffering the effect. Thus, the single save against the single triggering effect that it provides is taken right then. If it succeeds, the effect ends. If it fails, by RAW, the effect either endures or progresses (depending on the effect).
And as this is an Encounter Power, it has its one effect and then is gone until the unlikely event of the monster getting a Short Rest. It has no lasting power to in any way impact the end of the Hobgoblin's next turn, when the Hobgoblin will (in most cases) get another save should the first save have failed.