How do I : Pick 2 or more instances with the same value

Hey guys, I'm trying to assign random integer values to various instances. I want each instance to have its own unique value.

But when i randomly assign one there is a chance, a small one, that 2 or more instances might have the same value.

What should I do to prevent this?

Thanks for your help and time!

One solution is to put all numbers assigned in a array and each time you random a new number, you verify if it exists in the array yet, if not, put it in the array.

Thanks! Tried what you suggested, and got it to work! Many many thanks!