Web.config problem: The entry '' has already been added

We are going to production with our ASP.NET 2.0 application and we had a problem with configuration of logger from Micosoft Enterprise libraries. It depends on how the application is configured in IIS server. We had configured access to application from two different addresses and if we accessed from the nested one. It gives the error.

The error is described on the following url:

Enterprise Library Error: The entry 'ExceptionPolicy' has already been added