This collection already contains an address with scheme {0}. There can be at most one address per scheme in this collection. ...

This collection already contains an address with scheme {0}.  There can be at most one address per scheme in this collection. If your service is being hosted in IIS you can fix the problem by setting 'system.serviceModel/serviceHostingEnvironment/multipleSiteBindingsEnabled' to true or specifying 'system.serviceModel/serviceHostingEnvironment/baseAddressPrefixFilters'.