Domain event handlers are fired multiple times in case of registering multiple handlers for the same domain event.

[CanerPatir]

test case like following

 public class EventHandlerTests  
    {
        [Fact]
        public void should_work()
        {
            var resolver = IocBuilder.New.UseAutofacContainerBuilder()
                .UseStoveWithNullables(typeof(FakeBootstrapper)).UseStoveEventBus()
                .RegisterServices(s =>
                {
                    s.RegisterType<FakeBootstrapper>();
                    s.RegisterType<FakeSendToImageProcessorEventHandler>();
                    s.RegisterType<FakeVisualMappingCompletedEventHandler>();
                })
                .CreateResolver();


            var eventBus = resolver.Resolve<IEventBus>();

            eventBus.Register(typeof(VisualMappingCompletedEvent), new IocHandlerFactory(resolver, typeof(FakeSendToImageProcessorEventHandler)));

            eventBus.Register(typeof(VisualMappingCompletedEvent), new IocHandlerFactory(resolver, typeof(FakeVisualMappingCompletedEventHandler)));

            eventBus.Publish<VisualMappingCompletedEvent>(new VisualMappingCompletedEvent(), new Headers());
        }
    }


    public class FakeSendToImageProcessorEventHandler : EventHandlerBase, IEventHandler<VisualMappingCompletedEvent>, ITransientDependency
    {
        static int a ;
        public void Handle(VisualMappingCompletedEvent @event, Headers headers)
        {
            a++;
        }
    }

    public class FakeVisualMappingCompletedEventHandler : EventHandlerBase, IEventHandler<VisualMappingCompletedEvent>, ITransientDependency
    {
        static int b;
        public void Handle(VisualMappingCompletedEvent @event, Headers headers)
        {
            b++;
        }
    }

    public class FakeBootstrapper : StoveBootstrapper
    {

    }

In this case you will see a = 2, b = 2