The file "Star Destroyed" include both the events "Star Destroyed" and "Planet Destroyed", so you don't have to add both. The file "Planet Destroyed" is only there if you would like to see your planets threatened, but not the whole system at once if the star collapses.
Here are the event chances for these two files:
- For "Star Destroyed":
* Low event chance: 5%
* Medium event chance: 20%
* High event chance: 40%
- For "Planet Destroyed":
* Low event chance: 10%
* Medium event chance: 25%
* High event chance: 60*
If you want to change these values, you will have to edit the file: settings.txt after you have applied one of these two files. The lines to change are these ones:
Quote:
Event Percent Chance Low := 10
Event Percent Chance Medium := 25
Event Percent Chance High := 60
|
Although I wouldn't advice you to increase even more the odds for such catastrophic events, but if you want to, feel free to do so. 
Lastly, if you put either Planet Destroyed or Star Destroyed, you shouldn't remove these events and so you shouldn't change the files before the end of the game. As there is a warning before a Planet or a Star is destroyed (10 turns or 30 turns), removing these events once they are in the game is risky. An AI Empire may have been stricken by such an event, and has only received the warning but the event is still NOT finished. If you remove the event, the game will have problems when the event is applied.
In short, if you want to use either "Star Destroyed" or "Planet Destroyed", do *not* alter the events file during the game.
Hopefully, my post will make sense. Hopefully.