One in Turnback Cave, and one in the Distortion World?
No, you can only get one in the Distortion World or Turnback Cave. That will be the only one you can get.
hope this helps! :D
The only way you could get Giratina twice is if you:
1. Catch Giratina the first time
2.Trade Giratina to another platinum or diamond or pearl (along with other pokemon that you want to keep)
3. Reset the game
4. And catch Giratina again!
And there you have it! This is how you catch Giratina twice!
thats not true!! u cant catch giratina twice on pokemon platinum!!!