Cargo Jetty6x Slf4j Logging

I've been getting the following error when i trying to start my cargo/jetty6x plugin via maven.

org.apache.commons.logging.LogConfigurationException: org.apache.commons.logging.LogConfigurationExc
eption: org.apache.commons.logging.LogConfigurationException: Invalid class loader hierarchy.  You h
ave more than one version of 'org.apache.commons.logging.Log' visible, which is not allowed. (Caused
 by org.apache.commons.logging.LogConfigurationException: Invalid class loader hierarchy.  You have
more than one version of 'org.apache.commons.logging.Log' visible, which is not allowed.) (Caused by
 org.apache.commons.logging.LogConfigurationException: org.apache.commons.logging.LogConfigurationEx
ception: Invalid class loader hierarchy.  You have more than one version of 'org.apache.commons.logg
ing.Log' visible, which is not allowed. (Caused by org.apache.commons.logging.LogConfigurationExcept
ion: Invalid class loader hierarchy.  You have more than one version of 'org.apache.commons.logging.
Log' visible, which is not allowed.))
        at org.apache.commons.logging.impl.LogFactoryImpl.newInstance(LogFactoryImpl.java:543)
        at org.apache.commons.logging.impl.LogFactoryImpl.getInstance(LogFactoryImpl.java:235)
        at org.apache.commons.logging.impl.LogFactoryImpl.getInstance(LogFactoryImpl.java:209)
        at org.apache.commons.logging.LogFactory.getLog(LogFactory.java:351)
        at org.apache.jasper.servlet.JspServlet.(JspServlet.java:58)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
        at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
        at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
        at java.lang.reflect.Constructor.newInstance(Constructor.java:494)
        at java.lang.Class.newInstance0(Class.java:350)
        at java.lang.Class.newInstance(Class.java:303)
        at org.mortbay.jetty.servlet.Holder.newInstance(Holder.java:152)
        at org.mortbay.jetty.servlet.ServletHolder.doStart(ServletHolder.java:256)
        at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:40)
        at org.mortbay.jetty.servlet.ServletHandler.initialize(ServletHandler.java:593)
        at org.mortbay.jetty.servlet.Context.startContext(Context.java:139)
        at org.mortbay.jetty.webapp.WebAppContext.startContext(WebAppContext.java:1191)
        at org.mortbay.jetty.handler.ContextHandler.doStart(ContextHandler.java:481)
        at org.mortbay.jetty.webapp.WebAppContext.doStart(WebAppContext.java:434)
        at org.mortbay.component.AbstractLifeCycle.start(AbstractLifeCycle.java:40)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:585)

    org.slf4j
    jcl-over-slf4j
    1.5.3


    org.slf4j
    slf4j-api
    1.5.3


    org.slf4j
    slf4j-simple
    1.5.3

I have found this post Switching to SLF4J and this. I believe i have configured my slf4j jars correctly like so

org.codehaus.cargo
cargo-maven2-plugin

    false
    
       jetty6x
       embedded
    
    
 
     ${servlet.port}
 
                       


    
 start-container
 pre-integration-test
 
     start
     deploy
 
    
    
 stop-container
 post-integration-test
 
     stop
 
    

The standalone jetty plugin seems to run ok.

 org.mortbay.jetty
 maven-jetty-plugin
 6.1.6
 
     
  
      ${servlet.port}
      30000
  
     
     /
     stop
     9091