Generate username

Hi I am writing some logic that take first name from text file and Generate Employee ID for that Employee format First name Jack the id will be jak, put if I have to user with the same Employee with the same name or same user the Id format will be like this jak01


                List<string> empIDList = new List<string>();
                for (int i = 0; i < emp.Length; i++)
                {
                    for (int j = i + 1; j < emp.Length; j++)
                    {
                        if (emp[i].FirstName != emp[j].FirstName)
                        {
                            empIDList.Add(emp[i].FirstName.Substring(0, 3));
                            break;
                        }
                        else if (emp[i].FirstName == emp[j].FirstName)
                        {      numSufix++;
                            empIDList.Add(emp[i].FirstName.Substring(0, 3) + numSufix.ToString());
                            break;
                        }
                      

                    }
                }


Was their a question here? Or, just to show how to do something?