how did you make your bricks? are they cloned objects or did you just cut and paste? if you used cut & paste in the editor it makes another instance of that object, not a new object.
so if you Destroy that object, it will destroy all objects unless you pick them individually.. (by it's UID)
To avoid this, make sure you are always picking by UID. Or the event that triggers is based on an individual object like:
Sprite1 OnCollision - Destroy Sprite (this will only destroy that one instance of that object)
Button OnClick: Destroy Sprite - will destroy all Sprite instances at the same time.