原因是在web.config 文件中多次引用了“添加外部引用”
<system.serviceModel>
<bindings>
<basicHttpBinding>
<binding name="WebServiceSoap" />
<binding name="WebServiceSoap1" />
</basicHttpBinding>
</bindings>
<client>
<endpoint address="http://localhost:8054/WebService.asmx" binding="basicHttpBinding"
bindingConfiguration="WebServiceSoap" contract="ServiceReference.WebServiceSoap"
name="WebServiceSoap" />
<endpoint address="http://localhost:8054/WebService.asmx" binding="basicHttpBinding"
bindingConfiguration="WebServiceSoap1" contract="ServiceReference.WebServiceSoap"
name="WebServiceSoap1" />
</client>
</system.serviceModel>
所以删掉一个节点既可（如查引用的是WebServiceSoap，删掉WebServiceSoap1的有关节点，反之~）
也可以在页面引用的时候指定bindingConfiguration名字：
如：ServiceReference.WebServiceSoap web = new WebServiceSoapClient("WebServiceSoap");