Actually sorry that was bad advice. In this case, where you are destroying overlapping objects of the same sprite, UID might not work as well. You want to use Pick Nth instance instead:
[quote:23lxchy3]Pick Nth instance
Pick the instance at a given place in the internal list of picked objects. This is most useful used in sub-events to act on separate instances. For example, in a "Sprite collided with Sprite" event, Pick 0th instance and Pick 1st instance can be used to act on each instance involved in the collision separately.
If all objects are currently picked, this condition can also be used to pick an object by its index ID (IID). For more information, see common features.
You can pick Nth instance and destroy that instance in a loop until the Sprite collided/overlap with Sprite is no longer true (there is only one instance left).