How to gracefully add an existing key to dictionary c#

I have written some code that will gracefully add a key to dictionary. The goal was not to throw exception even if someone adds a key accidentally.  There are many arguments around this but it is the design that drove us to this. We could use a list that stores a class of Param with key and value as properties.

Code Snippet

1. using System;
2. using System.Collections.Generic;
3.  
4. namespace Example
5. {
6.     internal class Program
7.     {
8.         private static readonly Dictionary<string, int> dict = new Dictionary<string, int>();
9.  
10.         public static void Main(string[] args)
11.         {
12.             #region JunkCode
13.  
14.             AddParam("key", 0);
15.             AddParam("key", 0);
16.             AddParam("key", 0);
17.             AddParam("key", 0);
18.             AddParam("key", 0);
19.             AddParam("key", 0);
20.             AddParam("key", 0);
21.             AddParam("key", 0);
22.             AddParam("key", 0);
23.             AddParam("key", 0);
24.  
25.             #endregion
26.  
27.             foreach (var kvp in dict)
28.             {
29.                 Console.WriteLine(kvp.Key);
30.             }
31.  
32.             Console.Read();
33.         }
34.  
35.         private static void AddParam(string key, int value)
36.         {
37.             if (!dict.ContainsKey(key))
38.             {
39.                 dict.Add(key, value);
40.             }
41.             else
42.             {
43.                 dict.Add(SubstituteParamName(key), value);
44.             }
45.         }
46.  
47.         private static string SubstituteParamName(string paramName)
48.         {
49.             string baseParamName = paramName;
50.             string actualParamName = paramName;
51.             int index = 0;
52.  
53.             while (dict.ContainsKey(actualParamName))
54.             {
55.                 actualParamName = baseParamName + "(" + ++index + ")";
56.             }
57.             return actualParamName;
58.         }
59.     }
60. }