With a List box and a 2 counters you can make a unique random number generator.
1. you fill up the list box with the numbers you want.
2. Create the following events
In Counter 1 you put the Total amount of numbers that you want to select from the list
In Counter 2 the value gets stored from the list box.
So Counter 2 will be the unique number that you can use.
In my example it will trigger the events and based on the selected number you can trigger something else.