Compare a value to all other values in an array

Hey guys, I'm wondering if there's a way to compare a value in an array to all other values in an array.

An example of what I'm trying to do is as follows. I want to check to see if there are any duplicate coordinates assigned to a class object. Here's the kind of code I want to try to use, but everything I've tried so far has taxed the system too heavily.

 public class TestScript : MonoBehaviour {
 
 //As an example, I'll just use an integer array and integers.
 
 int[] testArray;
 int value
 
 void Start() {
   
   testArray = new int[2]
   value = random.Range(0, 1);
   testArray[1] = value;
   value = random.Range(0, 1);
   testArray[2] = value;
 
 }
 
 void TestFunction() {
   
   foreach(int value in testArray) 
     {
      /*
     I'm hoping there's some way to make an if statement (or something like 
     an if statement) comparing the instance of "value" being used to all
     other instances of "value" and activate if any other instances of value
     are the same (or at least something similar).
     */
     }
 
 }
 
 }

Thanks in advance! -Evan