Problem with jboss versions of xerces and xalan: XML Parsing Error: duplicate attribute in wsdl definitions

We are using a feature (SimpleWsdl11Definition) of spring ws (version 1.5.9) to serve wsdl files to the browser or to a client.
Our wsdl file has custom namespace prefixes like this:
<wsdl:definitions xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/" xmlns:bsf="http:/... >
It works in JBoss 5.1 and eap 6.0.0 but with JBoss 7.1.1 or the current 7.2 snapshot I get the following error when I enter the wsdl URL in the browser:
XML Parsing Error: duplicate attribute
Location: http://localhost:8080/sc-webservices/service/loginServiceWS.wsdl
Line Number 1, Column 671:<?xml version="1.0" encoding="UTF-8"?><wsdl:definitions xmlns:wsdl="http://schemas.xmlsoap.org/wsdl/" xmlns:bsf="http://
The wsdl served to the browser contains duplicates of the custom namespace prefixes defined in the original wsdl file packaged in a war inside an ear.
While debugging I only saw classes from jboss versions of xerces and xalan parsing the wsdl and serving the result to the client.