example to reproduce.

class 1:
package abc;
@Stateless(name="ws1")
@WebService(targetNamespace="http://example.org")
public class ws1 {
@WebMethod(operationName="method1")
public String method1(@WebParam(name="param1") int arg1, @WebParam(name="param2") int arg2)

{ return "TEST-WS1-Method1"; }

}

class 2:
package abc;
@Stateless(name="ws2")
@WebService(targetNamespace="http://example.org")
public class ws2 {

@WebMethod(operationName="method1")
public String method1(@WebParam(name="param1_new") int arg1, @WebParam(name="param2_new") int arg2)

{ return "TEST-WS2-Method1"; }

}

it's impossible to deploy this sample:
15:54:28,008 ERROR [MainDeployer] Could not start deployment: file:/home/nias/prog/jboss/server/default/tmp/deploy/tmp5876assek.ear-contents/assek.jar
org.jboss.ws.WSException: param1_new is not a valid property on class abc.jaxws.Method1
at com.sun.xml.bind.v2.runtime.JAXBContextImpl.getElementPropertyAccessor(JAXBContextImpl.java:926)
at org.jboss.ws.metadata.accessor.JAXBAccessorFactory.create(JAXBAccessorFactory.java:51)
at org.jboss.ws.metadata.umdm.EndpointMetaData.createAccessor(EndpointMetaData.java:713)
at org.jboss.ws.metadata.umdm.EndpointMetaData.eagerInitializeAccessors(EndpointMetaData.java:694)
at org.jboss.ws.metadata.umdm.EndpointMetaData.initializeInternal(EndpointMetaData.java:567)
at org.jboss.ws.metadata.umdm.EndpointMetaData.eagerInitialize(EndpointMetaData.java:553)
at org.jboss.ws.metadata.umdm.ServiceMetaData.eagerInitialize(ServiceMetaData.java:435)
at org.jboss.ws.metadata.umdm.UnifiedMetaData.eagerInitialize(UnifiedMetaData.java:196)
at org.jboss.wsf.stack.jbws.EagerInitializeDeploymentAspect.create(EagerInitializeDeploymentAspect.java:50)
at org.jboss.wsf.framework.deployment.DeploymentAspectManagerImpl.deploy(DeploymentAspectManagerImpl.java:118)
at org.jboss.wsf.container.jboss42.ArchiveDeployerHook.deploy(ArchiveDeployerHook.java:97)
at org.jboss.wsf.container.jboss42.DeployerInterceptor.start(DeployerInterceptor.java:90)
at org.jboss.deployment.SubDeployerInterceptorSupport$XMBeanInterceptor.start(SubDeployerInterceptorSupport.java:188)
at org.jboss.deployment.SubDeployerInterceptor.invoke(SubDeployerInterceptor.java:95)
at org.jboss.mx.server.Invocation.invoke(Invocation.java:88)
at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264)
at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:659)
at org.jboss.mx.util.MBeanProxyExt.invoke(MBeanProxyExt.java:210)
at $Proxy34.start(Unknown Source)
at org.jboss.deployment.MainDeployer.start(MainDeployer.java:1025)
at org.jboss.deployment.MainDeployer.start(MainDeployer.java:1015)
at org.jboss.deployment.MainDeployer.deploy(MainDeployer.java:819)
at org.jboss.deployment.MainDeployer.deploy(MainDeployer.java:782)
at sun.reflect.GeneratedMethodAccessor20.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:155)
at org.jboss.mx.server.Invocation.dispatch(Invocation.java:94)
at org.jboss.mx.interceptor.AbstractInterceptor.invoke(AbstractInterceptor.java:133)
at org.jboss.mx.server.Invocation.invoke(Invocation.java:88)
at org.jboss.mx.interceptor.ModelMBeanOperationInterceptor.invoke(ModelMBeanOperationInterceptor.java:142)
at org.jboss.mx.server.Invocation.invoke(Invocation.java:88)
at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264)
at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:659)
at org.jboss.mx.util.MBeanProxyExt.invoke(MBeanProxyExt.java:210)
at $Proxy9.deploy(Unknown Source)
at org.jboss.deployment.scanner.URLDeploymentScanner.deploy(URLDeploymentScanner.java:421)
at org.jboss.deployment.scanner.URLDeploymentScanner.scan(URLDeploymentScanner.java:634)
at org.jboss.deployment.scanner.AbstractDeploymentScanner$ScannerThread.doScan(AbstractDeploymentScanner.java:263)
at org.jboss.deployment.scanner.AbstractDeploymentScanner$ScannerThread.loop(AbstractDeploymentScanner.java:274)
at org.jboss.deployment.scanner.AbstractDeploymentScanner$ScannerThread.run(AbstractDeploymentScanner.java:225)

error caused by: w2.method1 has @WebParam(name) with a name (param1_new) different from ws1.method1 but has the same java-method-signature.
But both webservices should be independent and it should be possible to have same methods with different @WebParam names.
If i'm put the second WS to another package, the error disappears.