DiagnosticsTelemetryModule can get added more than once #1111

using System;
using Microsoft.ApplicationInsights;
using Microsoft.ApplicationInsights.Extensibility;
using Microsoft.ApplicationInsights.Extensibility.Implementation;

namespace ConsoleApp1
{
    class Program
    {
        static void Main(string[] args)
        {
            TelemetryConfiguration.Active.Dispose();
            new TelemetryClient();
            Console.WriteLine(TelemetryModules.Instance.Modules.Count);
        }
    }
}