It appears that the objects you pass to Silverlight through the WCF service are the same objects in your class library. In this case, the created web link objects will be assigned the same names. Linking to the library will give you 2 sets of objects with the same name.
If you install RIA services, once the function is the ability to share code between the client and server, simply by adding ".shared" to the class file names before the extensions. ASMX services so past centuries :)
if you do not want to learn how to provide RIA services for sharing objects through a large website separator (which I would recommend), you need to separate the data objects from the functionality on which you really want to share the client and server side.
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