Example: 2 plugins trying to register service or type on same location:

Plugin 1:
[2012-07-04 13:52:40,295] [653 ] [Main ] [DEBUG] - PluginManager: Trying to enable plugin 'SlimTv4HomeProvider' (id '727b7812-343d-4b35-8efd-1d499b70d848')
[2012-07-04 13:52:40,295] [653 ] [Main ] [INFO ] - PluginManager: Plugin 'SlimTv4HomeProvider' (id '727b7812-343d-4b35-8efd-1d499b70d848') enabled.

Plugin 2:
[2012-07-04 13:52:40,296] [654 ] [Main ] [DEBUG] - PluginManager: Trying to enable plugin 'SlimTVMPExtendedProvider' (id 'fd70fd97-cb53-4500-8632-0adcef359489')
[2012-07-04 13:52:40,297] [655 ] [Main ] [ERROR] - Error registering plugin items for plugin 'SlimTVMPExtendedProvider' (id 'fd70fd97-cb53-4500-8632-0adcef359489')
System.ArgumentException: At location '/ResourceProviders', a plugin item with id 'SlimTvProvider' is already registered
   at MediaPortal.Common.PluginManager.PluginRuntime.RegisterItem(PluginItemMetadata itemMetadata)
   at MediaPortal.Common.PluginManager.PluginRuntime.RegisterItems()
   at MediaPortal.Common.Services.PluginManager.PluginManager.TryEnable(PluginRuntime plugin, ICollection`1 autoActivatePlugins)


When you try to enter configuration, the whole screen won't load:

[2012-07-04 13:52:51,667] [12024 ] [InputMgr ] [ERROR] - WorkflowManager: Error updating menu actions in workflow model '545674f1-d92a-4383-b6c1-d758cecdbdf5' for workflow state 'e7422bb8-2779-49ab-bc99-e3f56138061b'
MediaPortal.Common.PluginManager.Exceptions.PluginInvalidStateException: Plugin 'SlimTVMPExtendedProvider' (id 'fd70fd97-cb53-4500-8632-0adcef359489') neither is enabled nor active; cannot request items in this state
   at MediaPortal.Common.Services.PluginManager.PluginManager.RequestItem(PluginItemRegistration itemRegistration, Type type, IPluginItemStateTracker stateTracker)
   at MediaPortal.Common.Services.PluginManager.PluginManager.RequestPluginItem(String location, String id, Type type, IPluginItemStateTracker stateTracker)
   at MediaPortal.Common.Services.PluginManager.PluginManager.RequestPluginItem[T](String location, String id, IPluginItemStateTracker stateTracker)
   at MediaPortal.Configuration.ConfigurationManagement.ConfigurationNode.LoadChildren()
   at MediaPortal.Configuration.ConfigurationManagement.ConfigurationNode.get_ChildNodes()
   at MediaPortal.UiComponents.Configuration.ConfigurationModel.NumSettingsSupported(IConfigurationNode sectionOrGroupNode)
   at MediaPortal.UiComponents.Configuration.ConfigurationModel.UpdateMenuActions(NavigationContext context, IDictionary`2 actions)
   at MediaPortal.UI.Services.Workflow.WorkflowManager.DoPushNavigationContext(WorkflowState state, NavigationContextConfig config)
[2012-07-04 13:52:51,668] [12025 ] [InputMgr ] [DEBUG] - WorkflowManager: Tidying up...
[2012-07-04 13:52:51,670] [12027 ] [InputMgr ] [ERROR] - WorkflowManager.NavigatePushInternal: Error in workflow model or screen
MediaPortal.Common.PluginManager.Exceptions.PluginInvalidStateException: Plugin 'SlimTVMPExtendedProvider' (id 'fd70fd97-cb53-4500-8632-0adcef359489') neither is enabled nor active; cannot request items in this state
   at MediaPortal.UI.Services.Workflow.WorkflowManager.DoPushNavigationContext(WorkflowState state, NavigationContextConfig config)
   at MediaPortal.UI.Services.Workflow.WorkflowManager.NavigatePushInternal(Guid stateId, NavigationContextConfig config)



h4. Steps to Reproduce
Enable both SlimTv4HomeProvider and SlimTvMpExtendedProvider for compilation.
Startup MP2
Enter "Settings" -> you return to home, error in log as above