Repro.cs

using System;
using System.Threading.Tasks;
using NServiceBus;
using NServiceBus.Persistence;

namespace Backend
{
    class Program
    {
        static void Main(string[] args)
        {
            StartBackend().GetAwaiter().GetResult();
            StartFrontend().GetAwaiter().GetResult();
        }

        static async Task StartBackend()
        {
            var config = new EndpointConfiguration("Backend");
            config.UseTransport<MsmqTransport>();
            var persistence = config.UsePersistence<NHibernatePersistence>();
            persistence.ConnectionString("data source=(local); initial catalog=nservicebus; integrated security=true");

            config.EnableInstallers();
            config.SendFailedMessagesTo("error");
            config.EnableOutbox();

            var endpoint = await Endpoint.Start(config);
            Console.WriteLine("Press <enter> to exit");
            Console.ReadLine();

            await endpoint.Stop();
        }

        static async Task StartFrontend()
        {
            var config = new EndpointConfiguration("Frontend");
            config.UseTransport<MsmqTransport>();
            var persistence = config.UsePersistence<NHibernatePersistence>();
            persistence.ConnectionString("data source=(local); initial catalog=nservicebus; integrated security=true");

            config.EnableInstallers();
            config.SendFailedMessagesTo("error");
            config.EnableOutbox();
            config.MakeInstanceUniquelyAddressable("ABC");

            var endpoint = await Endpoint.Start(config);
            Console.WriteLine("Press <enter> to exit");
            Console.ReadLine();

            await endpoint.Stop();
        }
    }
}