Reference Methods Exposed in Web Service

I have a web service developed in C# that uses a class library containing strongly typed datasets.  When a client application has references to the web service and the dataset class library, all the properties and methods of the dataset class library are exposed by the web service as well as through the reference to the dataset class library.

This causes "an ambiguous reference" error between the web service and the dataset class library.

Does a web service expose all of the properties and methods of all assemblies it references?  And, it there any way to prevent this?

Thanks,
Tom

TomBean