Custom tool warning: An item with the same key has already been added

I added a Service Reference for a WCF project; I had over a hundred endpoints in my ServiceHost web.config, and all my development was going slowly, so I decided to trim it down for now. I also decided to change the namespace while I was at it, so I just deleted the service referenc开发者_如何学Ce. The delete failed with an out of memory exception, so I finally just went to the file system and deleted the files. Then, the delete of the Service Reference worked. When I tried to add it back, I started getting the warning in the title above.

My question is this: where is the old Service Reference being "remembered", if that is what is going on, and if not, what else could be throwing this warning?

For the record, I am using the ASP.NET Development Server and VS 2008.

Thank you!

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I just fought through this one. I gather from searching the web it can happen for a number of different reasons. In my case, I had inadvertently referenced two different copies of the same dll in my Silverlight project. See the following helpful article: http://vanderbiest.org/blog/2009/07/13/custom-tool-warning-silverlight-add-web-reference-in-vs2008/

UPDATE: VS2010/"Update Service Reference" is adding a reference to the dll in the bin/debug folder duplicating my reference to the dll in the dll's project. I ended up deleting my reference and using the local bin dll instead. Odd. I have not had this problem in other similar projects.

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I got the same message. In my case the cause was a duplicate entry in the ServiceReferences.ClientConfig file.