Litium.Accelerator.Mvc.Routing.RequestModelHandler is used for api controllers request and will only be used if the litium-request-context http header is included with the request.
Litium.Accelerator.Mvc.Routing.RequestModelActionFilter is used for mvc controllers.
If you get the Litium.Accelerator.Mvc.Routing.RequestModelHandler.AccessorCleanup.Dispose() to be executed when you executing an mvc controller you are passing in the litium-request-context http header with the request that will make both of them to execute.
If you need to pass the request context into the mvc controller you should probably change to use another name of the http header to not get conflicts between them.